全文获取类型
收费全文 | 3818篇 |
免费 | 377篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 42篇 |
儿科学 | 146篇 |
妇产科学 | 169篇 |
基础医学 | 420篇 |
口腔科学 | 128篇 |
临床医学 | 250篇 |
内科学 | 818篇 |
皮肤病学 | 190篇 |
神经病学 | 134篇 |
特种医学 | 319篇 |
外国民族医学 | 7篇 |
外科学 | 573篇 |
综合类 | 110篇 |
预防医学 | 256篇 |
眼科学 | 49篇 |
药学 | 329篇 |
中国医学 | 22篇 |
肿瘤学 | 252篇 |
出版年
2023年 | 16篇 |
2022年 | 81篇 |
2021年 | 135篇 |
2020年 | 99篇 |
2019年 | 168篇 |
2018年 | 190篇 |
2017年 | 160篇 |
2016年 | 150篇 |
2015年 | 169篇 |
2014年 | 197篇 |
2013年 | 246篇 |
2012年 | 256篇 |
2011年 | 255篇 |
2010年 | 203篇 |
2009年 | 179篇 |
2008年 | 138篇 |
2007年 | 140篇 |
2006年 | 126篇 |
2005年 | 121篇 |
2004年 | 100篇 |
2003年 | 95篇 |
2002年 | 87篇 |
2001年 | 28篇 |
2000年 | 32篇 |
1999年 | 38篇 |
1998年 | 50篇 |
1997年 | 54篇 |
1996年 | 52篇 |
1995年 | 49篇 |
1994年 | 34篇 |
1993年 | 32篇 |
1992年 | 33篇 |
1991年 | 22篇 |
1990年 | 27篇 |
1989年 | 21篇 |
1988年 | 34篇 |
1987年 | 30篇 |
1986年 | 28篇 |
1985年 | 33篇 |
1984年 | 24篇 |
1983年 | 19篇 |
1982年 | 23篇 |
1981年 | 20篇 |
1980年 | 27篇 |
1979年 | 21篇 |
1978年 | 20篇 |
1977年 | 12篇 |
1976年 | 20篇 |
1971年 | 12篇 |
1967年 | 12篇 |
排序方式: 共有4214条查询结果,搜索用时 15 毫秒
11.
12.
13.
Diabetes mellitus is associated with disturbances in haemostasis that could contribute to the development of thrombotic complications.The present study was undertaken to determine the behavior of coagulation variables and fibrinolytic system in diabetes mellitus. Forty five diabetic patients and forty five matched controls were evaluated by doing the following haemostatic parameter, prothrombin time, partial thromboplastin time, thrombin time, coagulation factors assay II, VII, IX, & plasma fibrinogen, ADP-induced platelet aggregation, protein C, a2- antiplasmin, PAI and FDPs. Generally diabetic patients have high levels of fibrinogen, a2- antiplasmin, & PAI and lower level of protein C. Other haemostatic parameters did not show statistically significant difference between diabetic patients and control group. Significantally elevated levels of PAI, a2- antiplasmin together with low protein C level in diabetic patients may result in the disturbance of haemostatic balance favoring thrombotic events. Conclusion: High levels of plasma fibrinogen, a2A- antiplasmin with low plasma protein C activity could lead to a prothrombotic tendency in insulin dependent diabetic patients. Moreover, in non-insulin dependent diabetic patients, the above mentioned parameters together with high levels of ADP-induced platelet aggregation and plasminogen activator inhibitor may increase the risk of thrombotic complications. Obesity can be considered as an additional risk factor for development of thrombosis in diabetic patients. 相似文献
14.
Preferential recognition of human myocardial antigens by T lymphocytes from rheumatic heart disease patients. 总被引:2,自引:0,他引:2 下载免费PDF全文
M El-Demellawy R El-Ridi N I Guirguis M Abdel Alim A Kotby M Kotb 《Infection and immunity》1997,65(6):2197-2205
Acute rheumatic fever (ARF) and rheumatic heart disease (RHD) are autoimmune sequelae of upper respiratory infections with group A streptococci (GAS). To gain a better understanding of the pathogenesis of these diseases, we examined the in vitro proliferative responses of peripheral blood mononuclear cells (PBMC) from RHD patients to human myocardial proteins in a T-cell Western assay. A number of myocardial proteins fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis were recognized by PBMC from both patients and controls. However, PBMC from a significant percentage of RHD patients (40%) responded to a discrete band of myocardial proteins migrating with an apparent molecular mass of 50 to 54 kDa while none of the control subject PBMC responded to this protein band (P < or = 0.0001). To further investigate the link between infections with GAS and autoimmune carditis, we studied the proliferative responses of PBMC from patients and controls to myocardial proteins before and after in vitro stimulation of the cells with opsonized GAS isolated from ARF patients. Priming of PBMC with rheumatogenic GAS caused the percentage of RHD patients responding to the 50- to 54-kDa myocardial proteins to increase from 43 to 90% (P < or = 0.0284). By contrast, PBMC from control subjects failed to recognize the 50- to 54-kDa myocardial proteins even after stimulation with the opsonized streptococci (P < or = 0.0001). The assay sensitivity was increased from 40 to 90% after priming of a patient's cells with opsonized GAS, but the positive predictive value was 100% in both unprimed and primed cultures. Antibodies generated to partially purified 50- to 54-kDa myocardial proteins did not cross-react with either streptococcal homogenates, purified M protein, myosin, laminin, or vimentin, suggesting a lack of cross-reactivity at the humoral level. This study suggests that the 50- to 54-kDa myocardial proteins contain a putative antigen that is preferentially recognized by T cells from RHD patients and demonstrates that exposure to streptococcal antigens enhances the ability of patients to recognize these proteins. 相似文献
15.
Smoking and female infertility: a systematic review and meta-analysis 总被引:11,自引:10,他引:11
The high prevalence of smoking among women in their reproductive years
continues to be a matter of concern. The negative effects of smoking on
general health are well known, but smoking may also affect fertility. The
objective of the present study was to perform a systematic review of the
literature to determine whether there is an association between smoking and
risk of infertility in women of reproductive age, and to assess the size of
this effect. In the 12 studies used for this meta- analysis, the overall
value of the odds ratio (OR) for risk of infertility in women smokers
versus non-smokers was 1.60 [95% confidence interval (CI) 1.34-1.91].
Studies of subfertile women undergoing in-vitro fertilization (IVF)
treatment also show a reduction in fecundity among women smokers. A
meta-analysis of nine studies found an OR of 0.66 (95% CI 0.49-0.88) for
pregnancies per number of IVF- treated cycles in smokers versus
non-smokers. Despite the potential limitations of meta-analyses of
observational studies, the evidence presented in this review is compelling
because of the consistency of effect across different study designs, sample
size and types of outcome. However, continued reassurance is needed that
the calculated overall effect is not in fact due to confounding variables.
相似文献
16.
Positional cloning of the gene for X-linked retinitis pigmentosa 3: homology with the guanine-nucleotide-exchange factor RCC1 总被引:6,自引:7,他引:6
Roepman R; van Duijnhoven G; Rosenberg T; Pinckers AJ; Bleeker-Wagemakers LM; Bergen AA; Post J; Beck A; Reinhardt R; Ropers HH; Cremers FP; Berger W 《Human molecular genetics》1996,5(7):1035-1041
The gene for retinitis pigmentosa 3 (RP3), the most frequent form of X-
linked RP (XLRP), has been mapped previously to a chromosome interval of
less than 1000 kbp between the DXS1110 marker and the OTC locus at
Xp21.1-p11.4. Employing a novel technique, YAC Representation Hybridization
(YRH)', we have recently identified a small XLRP associated microdeletion
in this interval, as well as several putative exons including the 3' end of
a gene that was truncated by the deletion. cDNA library screening and
sequencing of a cosmid centromeric to the deletion has now enabled us to
identify numerous additional exons and to detect several point mutations in
patients with XLRP. The predicted gene product shows homology to RCC1, the
guanine-nucleotide- exchange factor (GEF) of the Ras-like GTPase Ran. Our
findings suggest that we have cloned the long-sought RP3 gene, and that it
may encode the GEF of a retina-specific GTP-binding protein.
相似文献
17.
Lundberg S; Rasmussen C; Berg AA; Lindblom B 《Human reproduction (Oxford, England)》1998,13(6):1490-1492
Falloposcopy is a transvaginal microendoscopic technique to explore the
human Fallopian tube from the uterotubal ostium to the fimbrial end.
Falloposcopy provides a unique possibility to visualize endotubal disease
and may be used therapeutically for removal of debris and for cutting down
filmy intraluminal adhesions. To assess the clinical performance of
falloposcopy as part of an infertility investigation, a total of 43 women
scheduled for laparoscopy as part of an investigation of infertility had a
falloposcopy performed in conjunction with the laparoscopy. All women were
investigated at Danderyd Hospital, Stockholm and Akademiska Hospital,
Uppsala, during 1995 and 1996. Images from the endosalpinx were obtained in
26 of 43 women (60.5%). In 10 women (23.3%), it was possible to obtain
images from both tubes. No images were of sufficient quality to describe
the entire tubal mucosa in detail. Falloposcopy represents a unique tool
for visualization of endotubal disease and may provide a valuable
instrument for in-vivo exploration of tubal physiology. However, certain
technical problems limit the usefulness of this method in routine clinical
practice. These technical problems have to be solved before falloposcopy
can achieve a central position in investigation and treatment of tubal
disease.
相似文献
18.
Blanton RE Salam EA Ehsan A King CH Goddard KA 《European journal of human genetics : EJHG》2005,13(5):660-668
A minority of individuals infected with the parasite Schistosoma mansoni develops hepatic fibrosis. HLA studies in Egypt and a candidate gene search in a Sudanese population indicate that the host's genetics contribute to disease susceptibility. In an Egyptian community, 32.7% of individuals 11 years and older had significant fibrosis by WHO ultrasound criteria. Linkage to 10 candidate genes was tested using 89 affected sibling pairs from 40 pedigrees in this community. The candidates included genes that initiate fibrosis, participate in collagen synthesis, or control collagen degradation. Two to four single-nucleotide polymorphisms (SNPs) were genotyped per locus, and 188 individuals were genotyped at 48 markers. Model-free modified Haseman-Elston analysis identified linkage to a SNP in the interferon gamma receptor locus (P=0.000001). There was also weak evidence for linkage to the interleukin 13-4 region and tissue growth factor beta 1. 相似文献
19.
Abdel Hakim Saad Rashika El Ridi Suher Zada Nasri Badir 《Developmental and comparative immunology》1984,8(4):835-844
Lymphocytes of thymus, spleen, peripheral blood (PB) and bone marrow (BM) collected from adult lizards, were cultured for 24 hr in the presence of 10?3M hydrocortisone acetate (HC) in order to assess the effect of in vitro HC on lizard T and B cell viability. The results indicated that HC induced stepwise, time-dependent mortality of the majority of thymocytes carrying T cell specific antigen(s) (TSA), 30–50% of T cells of spleen, PB and BM, and of a proportion of splenic B lymphocytes. Administration of 1 mg/g body weight HC to adult . lead to depletion of all TSA+ thymocytes. In contrast, T lymphocytes in the peripheral lymphoid compartments revealed both sensitivity and resistance to HC; similarly, B lymphocytes constituted susceptible and resistant subpopulations. 相似文献
20.
Babiker A Darbyshire J Pezzotti P Porter K Prins M Sabin C Walker AS;CASCADE Collaboration 《Journal of acquired immune deficiency syndromes (1999)》2003,32(3):303-310
The effect of HIV infection duration and CD4 cell count on short-term CD4 response was evaluated in treatment-naive seroconverters using logistic regression adjusted for CD4 count before highly active antiretroviral therapy (HAART) as well as for exposure category, age, sex, acute infection, and cohort. This association was also investigated in pretreated seroconverters, further adjusting for prior therapy. CD4 response (increase of >100 cells/microL at 6 months) was more likely if HAART was initiated in the first year following seroconversion (OR = 1.50 [95% CI: 1.07-2.10] compared with 2-5 years). There was no improvement in response from initiating HAART with CD4 count >350 cells/microL compared with 201 to 350 cells/microL. Below 200 cells/microL, however, the chance of a CD4 response appeared to be reduced (OR = 0.72 [95% CI: 0.40-1.28] for 0-200 cells/microL compared with 201-350 cells/microL, P = 0.26). Results were similar for pretreated individuals. Further, in pretreated individuals, a CD4 response was less likely if the CD4 nadir was lower than the pre-HAART CD4 count (OR = 0.18 [95% CI: 0.10-0.36] for >150 cells/microL difference between nadir and pre-HAART CD4 count vs. no difference, P < 0.001). Given the limitations of observational studies, particularly the inability to control for unmeasured confounders, these findings suggest that the initiation of HAART within the first year following seroconversion appears to improve short-term immunologic response. After that time, there is little to be gained in terms of short-term response from initiating HAART before reaching a CD4 count of 200 cells/microL. 相似文献