全文获取类型
收费全文 | 4081篇 |
免费 | 318篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 31篇 |
儿科学 | 128篇 |
妇产科学 | 61篇 |
基础医学 | 647篇 |
口腔科学 | 86篇 |
临床医学 | 490篇 |
内科学 | 794篇 |
皮肤病学 | 96篇 |
神经病学 | 395篇 |
特种医学 | 244篇 |
外科学 | 488篇 |
综合类 | 101篇 |
一般理论 | 5篇 |
预防医学 | 411篇 |
眼科学 | 65篇 |
药学 | 228篇 |
中国医学 | 10篇 |
肿瘤学 | 139篇 |
出版年
2021年 | 59篇 |
2020年 | 46篇 |
2019年 | 70篇 |
2018年 | 69篇 |
2017年 | 65篇 |
2016年 | 79篇 |
2015年 | 62篇 |
2014年 | 90篇 |
2013年 | 153篇 |
2012年 | 159篇 |
2011年 | 181篇 |
2010年 | 133篇 |
2009年 | 130篇 |
2008年 | 132篇 |
2007年 | 150篇 |
2006年 | 136篇 |
2005年 | 158篇 |
2004年 | 134篇 |
2003年 | 148篇 |
2002年 | 138篇 |
2001年 | 111篇 |
2000年 | 117篇 |
1999年 | 101篇 |
1998年 | 84篇 |
1997年 | 77篇 |
1996年 | 60篇 |
1995年 | 52篇 |
1994年 | 60篇 |
1993年 | 48篇 |
1992年 | 67篇 |
1991年 | 68篇 |
1990年 | 61篇 |
1989年 | 80篇 |
1988年 | 75篇 |
1987年 | 87篇 |
1986年 | 58篇 |
1985年 | 59篇 |
1984年 | 59篇 |
1983年 | 55篇 |
1982年 | 44篇 |
1980年 | 45篇 |
1979年 | 39篇 |
1978年 | 52篇 |
1977年 | 36篇 |
1976年 | 36篇 |
1975年 | 34篇 |
1974年 | 34篇 |
1973年 | 33篇 |
1972年 | 42篇 |
1970年 | 29篇 |
排序方式: 共有4419条查询结果,搜索用时 15 毫秒
41.
Anna Willis Jennifer Swann Joanne Thompson 《The British journal of general practice》2015,65(638):e593-e600
Background
Improving child health and wellbeing in England was the key focus of the Chief Medical Officer’s Annual Report 2012, which recommended that all children with long-term conditions (LTCs) have a named GP responsible for their care. Little is known, however, about practitioners’ views and experiences of supporting children with LTCs in primary care.Aim
To explore practitioners’ views of supporting children with LTCs and their families in primary care.Design and setting
Qualitative interview study in primary care settings in South Yorkshire, England.Method
Interviews explored practitioners’ views and experiences of supporting children with asthma, cystic fibrosis, type 1 diabetes, and epilepsy. Interviews were audiotaped, transcribed verbatim, and analysed using the framework approach.Results
Nineteen practitioners were interviewed: 10 GPs, five practice nurses, and four nurse practitioners. The GPs’ clinical roles included prescribing and concurrent illness management; nurse practitioners held minor illness clinics; and practice nurses conduct asthma clinics and administer immunisations. GPs were coordinators of care and provided a holistic service to the family. GPs were often unsure of their role with children with LTCs, and did not feel they had overall responsibility for these patients. Confidence was dependent on experience; however, knowledge of GPs’ own limits and accessing help were felt to be more important than knowledge of the condition.Conclusion
Primary care has a valuable role in the care of children with LTCs and their families. This study suggests that improving communication between services would clarify roles and help improve the confidence of primary care practitioners. 相似文献42.
V.K. de Sá T.P. Rocha AL. Moreira F.A. Soares T. Takagaki L. Carvalho A.G. Nicholson V.L. Capelozzi 《Brazilian journal of medical and biological research》2015,48(11):1039-1047
We collected a series of 136 lung/bronchial and 56 matched lung parenchyma tissue
samples from patients who underwent lung/bronchial biopsies and presented invasive
carcinoma after lung surgery. The lung/bronchial samples included basal cell
hyperplasia, squamous metaplasia, moderate dysplasia, adenomatous hyperplasia, severe
dysplasia, squamous cell carcinoma and adenocarcinoma. Matched lung parenchyma tissue
samples included 25 squamous cell carcinomas and 31 adenocarcinomas.
Immunohistochemistry was performed to analyze for the distribution of hyaluronidase
(Hyal)-1 and −3, and hyaluronan synthases (HAS)-1, −2, and −3. Hyal-1 showed
significantly higher expression in basal cell hyperplasia than in moderate dysplasia
(P=0.01), atypical adenomatous hyperplasia (P=0.0001), or severe dysplasia (P=0.03).
Lower expression of Hyal-3 was found in atypical adenomatous hyperplasia than in
basal cell hyperplasia (P=0.01) or moderate dysplasia (P=0.02). HAS-2 was
significantly higher in severe dysplasia (P=0.002) and in squamous metaplasia
(P=0.04) compared with basal cell hyperplasia. HAS-3 was significantly expressed in
basal cell hyperplasia compared with atypical adenomatous hyperplasia (P=0.05) and
severe dysplasia (P=0.02). Lower expression of HAS-3 was found in severe dysplasia
compared with squamous metaplasia (P=0.01) and moderate dysplasia (P=0.01).
Epithelial Hyal-1 and −3 and HAS-1, −2, and −3 expressions were significantly higher
in pre-neoplastic lesions than in neoplastic lesions. Comparative Cox multivariate
analysis controlled by N stage and histologic tumor type showed that patients with
high HAS-3 expression in pre-neoplastic cells obtained by lung/bronchial biopsy
presented a significantly higher risk of death (HR=1.19; P=0.04). We concluded that
localization of Hyal and HAS in lung/bronchial pre-neoplastic and neoplastic lesions
was inversely related to malignancy, which implied that visualizing these factors
could be a useful diagnostic procedure for suspected lung cancer. Finalizing this
conclusion will require a wider study in a randomized and prospective trial. 相似文献
43.
Liudmila Kulik Finnegan B. Hewitt Van C. Willis Rosa Rodriguez Stephen Tomlinson V. Michael Holers 《Molecular immunology》2015
Although reagents are available to block mouse complement receptor type 2 and/or type 1 (CR2/CR1, CD21/CD35) function in acute or short term models of human disease, a mouse anti-rat antibody response limits their use in chronic models. We have addressed this problem by generating in Cr2−/− mice a mouse monoclonal antibody (mAb 4B2) to mouse CR2/CR1. The binding of murine mAb 4B2 to CR2/CR1 directly blocked C3dg (C3d) ligand binding. In vivo injection of mAb 4B2 induced substantial down regulation of CR2 and CR1 from the B cell surface, an effect that lasted six weeks after a single injection of 2 mg of mAb. The 4B2 mAb was studied in vivo for the capability to affect immunological responses to model antigens. Pre-injection of mAb 4B2 before immunization of C57BL/6 mice reduced the IgG1 antibody response to the T-dependent antigen sheep red blood cells (SRBC) to a level comparable to that found in Cr2−/− mice. We also used the collagen-induced arthritis (CIA) model, a CR2/CR1-dependent autoimmune disease model, and found that mice pre-injected with mAb 4B2 demonstrated substantially reduced levels of pathogenic IgG2a antibodies to both the bovine type II collagen (CII) used to induce arthritis and to endogenous mouse CII. Consistent with this result, mice pre-injected with mAb 4B2 demonstrated only very mild arthritis. This reduction in disease, together with published data in CII-immunized Cr2−/− mice, confirm both that the arthritis development depends on CR2/CR1 receptors and that mAb 4B2 can be used to induce biologically relevant receptor blockade. Thus mAb 4B2 is an excellent candidate for use in chronic murine models to determine how receptor blockage at different points modifies disease activity and autoantibody responses. 相似文献
44.
Convergent inputs from articular,cutaneous and muscle receptors onto ascending tract cells in the cat spinal cord 总被引:2,自引:0,他引:2
H. -G. Schaible R. F. Schmidt W. D. Willis 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1987,66(3):479-488
Summary 1.Responses were recorded from 160 ascending tract cells in segments L4 to L6 of the spinal cord in chloralose anaesthetized, spinalized cats. The tract cells were identified by antidromic activation following stimulation of pathways in the lateral and ventral funiculi at the level of the spinal cord transection at the thoracolumbar junction. Axonal conduction velocities ranged from 9 to 114 m/s. 2. A sample of 152 of the neurones examined could be subdivided according to the distribution of their receptive fields into 49 cells activated just from receptors located in skin (s cells), 17 neurones excited by receptors in deep tissues (d cells), 15 units with a convergent input from receptors in skin and deep tissues (sd cells), and 25 neurones with a convergent input from the knee joint and either skin (sj cells), deep tissues (dj cells) or both (sdj cells). No receptive fields could be demonstrated for the remaining 46 neurones. 3. S and sj cells were found almost exclusively in the dorsal horn, whereas many d, sd, sdj and dj units were in the ventral horn. Almost all of the cells that lacked receptive fields were in the ventral horn or intermediate grey. 4. Ninety-one of 158 cells (56%) demonstrated no background activity. Of these, 43 cells (27%) lacked receptive fields. Many of the silent neurones were in the ventral horn, but some were in the dorsal horn. Of 25 cells having knee joint input, 18 (72%) had background activity. 5. All of the neurones that had a receptive field in the knee joint also had a convergent input from receptors in other tissues. In 3 cases, there was a receptive field in the skin over the foot (sj cells). For 16 cells, receptive fields included not only the knee joint but also skin and deep tissue (sdj cells). Usually, the cutaneous receptive field was near the knee joint, but sometimes it was remote, such as on the foot. The deep receptive fields were chiefly in the muscles of the thigh and/or leg. For 6 dj cells, the receptive fields included not only the knee joint but also deep fields like those of sdj cells. 6. Cutaneous receptive fields were classified as low threshold (cells excited best by innocuous intensities of mechanical stimulation), wide dynamic range (cells activated by weak mechanical stimuli, but the best responses were to noxious stimuli) or high threshold (innocuous stimuli had little effect, but noxious mechanical stimuli produced a vigorous discharge). Similarly, stimulation of the knee joint with weak mechanical stimuli could excite some neurones, while others could be activated by weak or strong articular stimuli but were excited best by noxious stimuli, and still other neurones were activated by knee joint stimuli only if the intensity was noxious. 7. In several instances, contralateral receptive fields were noted. These were generally in deep tissue or in the knee joint. 8. It was concluded that many of the responses to articular stimulation of the spinal cord ascending tract cells examined in this study could have been mediated by the fine afferent fibres that supply the knee joint. Although further work will be required to determine which particular ascending tracts transmit nociceptive information concerning the knee joint, it can be proposed that many of the responses demonstrated here were likely to play a role in either joint pain of in triggering responses associated with joint pain. 相似文献
45.
Virginia P. Johnson Willis C. Sutliff 《American journal of medical genetics. Part A》1994,52(2):184-187
Partial duplication of 10q is a recognizable clinical entity. In most of the reported cases, the trisomic segment is identified by a balanced translocation state in a parent. Verification remains a problem in de novo cases. However, the recent availability of whole chromosome probes allows for confirmatory diagnosis of suspected cases. We describe a case of de novo duplication (10q) wiht verification using DNA in situ hybridization. © 1994 Wiley-Liss, Inc. 相似文献
46.
Tyner JW Walters DK Willis SG Luttropp M Oost J Loriaux M Erickson H Corbin AS O'Hare T Heinrich MC Deininger MW Druker BJ 《Blood》2008,111(4):2238-2245
Despite vast improvements in our understanding of cancer genetics, a large percentage of cancer cases present without knowledge of the causative genetic events. Tyrosine kinases are frequently implicated in the pathogenesis of numerous types of cancer, but identification and validation of tyrosine kinase targets in cancer can be a time-consuming process. We report the establishment of an efficient, functional screening assay using RNAi technology to directly assess and compare the effect of individually targeting each member of the tyrosine kinase family. We demonstrate that siRNA screening can identify tyrosine kinase targets containing activating mutations in Janus kinase (JAK) 3 (A572V) in CMK cells and c-KIT (V560G) in HMC1.1 cells. In addition, this assay identifies targets that do not contain mutations, such as JAK1 and the focal adhesion kinases (FAK), that are crucial to the survival of the cancer cells. This technique, with additional development, might eventually offer the potential to match specific therapies with individual patients based on a functional assay. 相似文献
47.
Rosenfeld CR Zagariya AM Liu XT Willis BC Fluharty S Vidyasagar D 《Pediatric research》2008,63(3):251-256
The pulmonary renin-angiotensin system (RAS) contributes to inflammation and epithelial apoptosis in meconium aspiration. It is unclear if both angiotensin II receptors (ATR) contribute, where they are expressed and if meconium modifies subtype expression. We examined ATR subtypes in 2 wk rabbit pup lungs before and after meconium exposure and with and without captopril pretreatment or type 1 receptor (AT1R) inhibition with losartan, determining expression and cellular localization with immunoblots, RT-PCR and immunohistochemistry, respectively. Responses of cultured rat alveolar type II pneumocytes were also examined. Type 2 ATR were undetected in newborn lung before and after meconium instillation. AT1R were expressed in pulmonary vascular and bronchial smooth muscle and alveolar and bronchial epithelium. Meconium increased total lung AT1R protein approximately 3-fold (p = 0.006), mRNA 29% (p = 0.006) and immunostaining in bronchial and alveolar epithelium and smooth muscle, which were unaffected by captopril and losartan. Meconium also increased AT1R expression >3-fold in cultured type II pneumocytes and caused concentration-dependent cell death inhibited by losartan. Meconium increases AT1R expression in newborn rabbit lung and cultured type II pneumocytes and induces AT1R-mediated cell death. The pulmonary RAS contributes to the pathogenesis of meconium aspiration through increased receptor expression. 相似文献
48.
This study examines the possibility that endogenous adenosine modulates efficiency in isovolumic perfused rat hearts stimulated with isoproterenol or norepinephrine. Efficiency in these hearts is calculated as the rate of pressure work divided by the myocardial oxygen consumption. Within 2 min of infusion of isoproterenol (50 nM), heart rate increased by 35%, the rate pressure product by 290%, oxygen consumption by 142%, and efficiency by 67%. Infusion of adenosine deaminase (2–4 IU/ml), or 8-phenyltheophylline (5 M), into stimulated hearts augmented the increase in heart rate by 40–45%, rate-pressure product by 18–20%, and oxygen consumption by 50–55%. Efficiency was reduced by 30–35%. Adenosine release into the coronary venous effluent increased from 195±20 pmol/min/g to 2400±180 pmol/min/g after 5 min. A similar pattern of results was observed when norepinephrine (0.1 mM) was used. The results indicate that extracellular adenosine, released by catecholamine treatment, inhibits the effects of the catecholamines on rate and contractility. Consequently, adenosine reduces cardiac work (rate-pressure product), but in so doing, improves efficiency. 相似文献
49.
50.
Mutation spectrum and genotype-phenotype analyses in Cowden disease and Bannayan-Zonana syndrome, two hamartoma syndromes with germline PTEN mutation 总被引:22,自引:1,他引:22
Marsh DJ; Coulon V; Lunetta KL; Rocca-Serra P; Dahia PL; Zheng Z; Liaw D; Caron S; Duboue B; Lin AY; Richardson AL; Bonnetblanc JM; Bressieux JM; Cabarrot-Moreau A; Chompret A; Demange L; Eeles RA; Yahanda AM; Fearon ER; Fricker JP; Gorlin RJ; Hodgson SV; Huson S; Lacombe D; Eng C 《Human molecular genetics》1998,7(3):507-515
The tumour suppressor gene PTEN , which maps to 10q23.3 and encodes a 403
amino acid dual specificity phosphatase (protein tyrosine phosphatase;
PTPase), was shown recently to play a broad role in human malignancy.
Somatic PTEN deletions and mutations were observed in sporadic breast,
brain, prostate and kidney cancer cell lines and in several primary tumours
such as endometrial carcinomas, malignant melanoma and thyroid tumours. In
addition, PTEN was identified as the susceptibility gene for two hamartoma
syndromes: Cowden disease (CD; MIM 158350) and Bannayan-Zonana (BZS) or
Ruvalcaba-Riley-Smith syndrome (MIM 153480). Constitutive DNA from 37 CD
families and seven BZS families was screened for germline PTEN mutations.
PTEN mutations were identified in 30 of 37 (81%) CD families, including
missense and nonsense point mutations, deletions, insertions, a
deletion/insertion and splice site mutations. These mutations were
scattered over the entire length of PTEN , with the exception of the first,
fourth and last exons. A 'hot spot' for PTEN mutation in CD was identified
in exon 5 that contains the PTPase core motif, with 13 of 30 (43%) CD
mutations identified in this exon. Seven of 30 (23%) were within the core
motif, the majority (five of seven) of which were missense mutations,
possibly pointing to the functional significance of this region. Germline
PTEN mutations were identified in four of seven (57%) BZS families studied.
Interestingly, none of these mutations was observed in the PTPase core
motif. It is also worthy of note that a single nonsense point mutation,
R233X, was observed in the germline DNA from two unrelated CD families and
one BZS family. Genotype-phenotype studies were not performed on this small
group of BZS families. However, genotype-phenotype analysis inthe group of
CD families revealed two possible associations worthy of follow-up in
independent analyses. The first was an association noted in the group of CD
families with breast disease. A correlation was observed between the
presence/absence of a PTEN mutation and the type of breast involvement
(unaffected versus benign versus malignant). Specifically and more
directly, an association was also observed between the presence of a PTEN
mutation and malignant breast disease. Secondly, there appeared to be an
interdependent association between mutations upstream and within the PTPase
core motif, the core motif containing the majority of missense mutations,
and the involvement of all major organ systems (central nervous system,
thyroid, breast, skin and gastrointestinal tract). However, these
observations would need to be confirmed by studying a larger number of CD
families.
相似文献