首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   9855篇
  免费   862篇
  国内免费   38篇
耳鼻咽喉   26篇
儿科学   485篇
妇产科学   185篇
基础医学   1493篇
口腔科学   348篇
临床医学   1028篇
内科学   1742篇
皮肤病学   176篇
神经病学   1077篇
特种医学   340篇
外科学   1102篇
综合类   329篇
一般理论   10篇
预防医学   836篇
眼科学   115篇
药学   761篇
中国医学   69篇
肿瘤学   633篇
  2021年   154篇
  2020年   114篇
  2019年   154篇
  2018年   167篇
  2017年   131篇
  2016年   147篇
  2015年   156篇
  2014年   224篇
  2013年   324篇
  2012年   476篇
  2011年   443篇
  2010年   335篇
  2009年   261篇
  2008年   436篇
  2007年   401篇
  2006年   411篇
  2005年   394篇
  2004年   351篇
  2003年   371篇
  2002年   330篇
  2001年   296篇
  2000年   289篇
  1999年   252篇
  1998年   147篇
  1997年   145篇
  1996年   119篇
  1995年   124篇
  1994年   98篇
  1993年   97篇
  1992年   189篇
  1991年   220篇
  1990年   167篇
  1989年   219篇
  1988年   229篇
  1987年   266篇
  1986年   212篇
  1985年   240篇
  1984年   146篇
  1983年   96篇
  1982年   84篇
  1981年   86篇
  1980年   76篇
  1979年   108篇
  1978年   108篇
  1977年   95篇
  1976年   70篇
  1975年   75篇
  1974年   77篇
  1973年   72篇
  1972年   72篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Antagonists acting at the 5-hydroxytryptamine3 receptor are potent anti-emetic agents in cases of cytotoxic- and radiation-induced vomiting, and binding sites for these compounds have been described in brainstem areas known to be involved in mediation of nausea and vomiting. We have used autoradiography to examine the distribution of one of these antagonists, [3H]granisetron in the caudal brainstem of the ferret, a commonly used animal model for physiological investigations of emesis. The highest density of binding sites was found to be in the dorsomedial region of the nucleus of the solitary tract, the principal terminus for gastric vagal afferent fibres. Lower levels of binding were observed in the area postrema and the dorsal motor nucleus of the vagus. Following unilateral nodose ganglion excision, displaceable binding of [3H]granisetron in the nucleus of the solitary tract was attenuated on the ipsilateral side by 65%. Bilateral subdiaphragmatic vagotomy abolished binding of [3H]granisetron in the entire dorsal vagal complex. These results provide strong circumstantial evidence that 5-hydroxytryptamine3 receptors are located on vagal afferent terminals in the ferret brainstem.  相似文献   
82.
Between 1965 and 1986 we saw 36 children with enuresis and urinary tract infection in association with “inversion” of facial expression when laughing. Urologic work-up of these patients disclosed characteristic findings of mild neuropathic bladder in all cases, with severe urinary tract damage in most of them. The clear association of distortion in facial expression and neuropathic bladder with resultant damage to the genitourinary tract should prompt urological evaluation of individuals with “inversion” of facial expression. About two thirds of the patients also had moderate to severe constipation. We suggest the term urofacial syndrome for this disorder. The occurrence of the disorder in multiple sibs, normal parents, increased parental consanguinity, and equal sex ratio indicate autosomal recessive inheritance.  相似文献   
83.
We present a girl with mild manifestations of the Brachmann-de Lange syndrome (BDLS) with gradual change of the phenotype. Her findings support the hypothosis of variability of the phenotypic spectrum of the disorder.  相似文献   
84.
Chromosomal deletions, associated with the loss of normal function of tumour suppressor genes, have been identified in a variety of both familial and sporadic human cancers. Although the molecular pathology of ovarian cancer is not understood, several studies have reported deletions in chromosome 17 in ovarian tumours. We have used 13 restriction site polymorphic, microsatellite, and variable number tandem repeat markers to make a detailed analysis of chromosome 17 deletions in 12 benign and 19 malignant ovarian tumours. Two benign and 11 malignant tumours were informative for at least one marker on each arm of the chromosome. Loss of heterozygosity (LOH) was detected in both arms (by all informative markers) in 5 malignant tumours from four women (three with the disease at FIGO stage la). In a further bilateral ovarian tumour a partial LOH affecting 17q22-q25 was present in one ovary only. By contrast to a number of previous studies, none of the 19 malignant and 12 benign tumours showed ERBB2 (17q12ndash;22) amplification. The data presented show that the loss of a whole copy of chromosome 17 is a frequent and relatively early event in the development of some ovarian cancers. This suggests the possible involvement of multiple chromosome 17 loci in the pathogenesis of ovarian cancer. Equally plausible is that the loss of a whole chromosome copy could be the product of chromosomal instabilities induced by loss of the normal allele of tumour suppressors, such as TP53, located on this chromosome. © 1993 Wiley-Liss, Inc.  相似文献   
85.
J Reynolds  L Gyure  E Andrew  J G Hall 《Immunology》1980,39(4):463-467
Bile or thoracic duct lymph, collected from rats 7-9 days after suspensions of B. abortus, S. typhi or SRBC had been injected into the Peyer''s patches, contained high titres of specific agglutinins. Samples of these fluids were injected i.v. into unimmunized, syngeneic recipients and the partitioning between blood and bile of the injected antibodies was studied and found to depend on the source and class of the antibody. IgA antibodies from lymph plasma disappeared rapidly from the recipients'' blood and half of the dose was recovered in the bile within 2 h of its injection. IgA antibodies which had been collected from bile and so had previously traversed the liver and acquired secretory component, appeared in the recipients'' bile much less rapidly so that less than half of the dose entered the bile over a period of 40 h. Passively administered IgG antibodies did not enter the recipients'' bile to any significant extent and specific haemolysins never appeared in the bile after either passive or active immunization.  相似文献   
86.
Cellular mechanisms contributing to renewal of terminal bronchioles remain poorly defined. Our previous studies identified pollutant-resistant Clara cell secretory protein (CCSP)-expressing stem cells that localize to the neuroepithelial body (NEB) and contribute to renewal of the proximal bronchiolar epithelium. However, activation of NEB-associated stem cells is unlikely to contribute to renewal of terminal bronchiolar epithelium because of the paucity of NEBs at this location. Goals of this study were to determine the location and properties of cells contributing to renewal of terminal bronchioles after Clara cell depletion. Pollutant-resistant CCSP-expressing cells were identified that localized to the bronchoalveolar duct junction (BADJ) and contribute to restoration of a phenotypically diverse epithelium. CCSP-expressing cells comprise the predominant proliferative population in initial terminal bronchiolar repair and include a population of label-retaining cells suggesting that they maintain characteristics of a stem cell population. Furthermore, immunohistochemical co-localization studies involving CCSP and the NEB-specific marker calcitonin gene-related peptide indicate that BADJ-associated CCSP-expressing stem cells function independently of NEB microenvironments. These studies identify a BADJ-associated, NEB-independent, CCSP-expressing stem cell population in terminal bronchioles and support the notion that regiospecific stem cell niches function to maintain epithelial diversity after injury.  相似文献   
87.
We have used serological proteome analysis in conjunction with tandem mass spectrometry to identify and sequence a novel protein, Mtb81, which may be useful for the diagnosis of tuberculosis (TB), especially for patients coinfected with human immunodeficiency virus (HIV). Recombinant Mtb81 was tested by an enzyme-linked immunosorbent assay to detect antibodies in 25 of 27 TB patients (92%) seropositive for HIV as well as in 38 of 67 individuals (57%) who were TB positive alone. No reactivity was observed in 11 of 11 individuals (100%) who were HIV seropositive alone. In addition, neither sera from purified protein derivative (PPD)-negative (0 of 29) nor sera from healthy (0 of 45) blood donors tested positive with Mtb81. Only 2 of 57 of PPD-positive individuals tested positive with Mtb81. Sera from individuals with smear-positive TB and seropositive for HIV but who had tested negative for TB in the 38-kDa antigen immunodiagnostic assay were also tested for reactivity against Mtb81, as were sera from individuals with lung cancer and pneumonia. Mtb81 reacted with 26 of 37 HIV(+) TB(+) sera (70%) in this group, compared to 2 of 37 (5%) that reacted with the 38-kDa antigen. Together, these results demonstrate that Mtb81 may be a promising complementary antigen for the serodiagnosis of TB.  相似文献   
88.

Objective

The purpose of this study was to evaluate websites providing information on treatment for depression to the public, and to evaluate changes in the quality of website information over time.

Methods

Websites (N?=?25) addressing depression treatment were identified through the use of the Google search engine and by suggestions from healthcare professionals. Each website was evaluated based on the extent to which it addressed content areas deemed important by the public identified in previous research, overall quality as determined by the DISCERN, and reading level.

Results

Overall, the quality of depression websites varied greatly. The majority of websites did not adequately answer the public’s questions about treatment options, and presented higher quality information in the area of pharmacological treatments as compared to other treatment options. An average reading level of 10.0 was found across websites. Upon re-evaluation, only 14 of 25 websites added new content, and the majority of websites did not improve in their overall website quality (as measured by the DISCERN).

Conclusion and Practice Implications

Websites could be improved by addressing important questions that consumers have concerning depression, as well as by creating higher quality content in the areas of psychological, neurotherapeutic, and alternative treatments.  相似文献   
89.
To investigate the dissemination of vancomycin-resistant Enterococcus faecium (VREF) in a 728-bed tertiary-care hospital, all clinical VREF isolates recovered from June 1992 to June 1997 were typed by pulsed-field gel electrophoresis, and the transfer histories of the patients were documented. A total of 413 VREF isolates from urine (52%), wounds (16%), blood (11%), catheter tips (6%), and other sites (15%) were studied. VREF specimens mostly came from patients on wards (66%) but 34% came from patients in an intensive care unit. The number of VREF isolates progressively increased over time, with higher rates of isolation during the winter months and lower rates in the late summer months. Four distinct banding patterns were detected by pulsed-field gel electrophoresis among 316 samples (76%). Strain A (122 samples; 30%) appeared in June 1992 as the first VREF strain and was found until December 1994 throughout the entire hospital. Type B (92 samples; 22%) was initially detected in January 1994 and disappeared in November 1996. Strain C (10 samples; 2%) was limited to late 1996 and early 1997. Strain D (92 samples; 22%) showed two major peaks during March 1996 to August 1996 and January 1997 to February 1997. Unrelated strains (97 samples; 24%) appeared 1 year after the appearance of the first VREF isolate, and the numbers increased slightly over the years. Nosocomial acquisition (i.e., no known detection prior to admission and first isolation from cultures performed with samples retrieved >/=2 days after hospitalization) was found for 316 (91%) of 347 patients. Despite the implementation of Centers for Disease Control and Prevention guidelines, the proportion of related strains and high number of nosocomial cases of infection indicate a high transmission rate inside the hospital. The results imply an urgent need for stringent enforcement of more effective infection control measures.  相似文献   
90.
T101 monoclonal antibody recognizes a pan-T-cell antigen present on normal T cells and also found in high concentrations in cutaneous T-cell lymphoma. We used this antibody, radiolabeled with 111In, in gamma-camera imaging to detect sites of metastatic cutaneous T-cell lymphoma in 11 patients with advanced disease. In all patients, [111In]T101 concentrated in pathologically or clinically detected nodes, including those in several previously unsuspected nodal regions. Concentrations (per gram of tissue) ranged from 0.01 to 0.03 percent of the injected dose and were consistently 10 to 100 times higher than previously reported on radioimmunodetection. Focal uptake was seen in skin tumors and heavily infiltrated erythroderma but not in skin plaques. The specificity of tumor targeting was documented by control studies with [111In]chloride or [111In]9.2.27 (anti-melanoma) monoclonal antibody. Increasing the T101 dose (1 to 50 mg) altered distribution in nontumor tissues. These studies suggest that imaging with [111In]T101 may be of value in identifying sites of cutaneous T-cell lymphoma. In contrast to the targeting of solid tumors, the mechanism of localization appears to be related to binding to T cells, which can then carry the radioactivity to involved sites.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号