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   1594篇
  免费   69篇
  国内免费   4篇
耳鼻咽喉   13篇
儿科学   127篇
妇产科学   54篇
基础医学   188篇
口腔科学   27篇
临床医学   72篇
内科学   307篇
皮肤病学   42篇
神经病学   91篇
特种医学   44篇
外科学   285篇
综合类   33篇
一般理论   1篇
预防医学   46篇
眼科学   56篇
药学   131篇
中国医学   6篇
肿瘤学   144篇
  2023年   13篇
  2022年   27篇
  2021年   49篇
  2020年   18篇
  2019年   28篇
  2018年   51篇
  2017年   34篇
  2016年   33篇
  2015年   48篇
  2014年   53篇
  2013年   80篇
  2012年   122篇
  2011年   126篇
  2010年   66篇
  2009年   57篇
  2008年   90篇
  2007年   93篇
  2006年   72篇
  2005年   74篇
  2004年   71篇
  2003年   59篇
  2002年   49篇
  2001年   19篇
  2000年   44篇
  1999年   33篇
  1998年   11篇
  1997年   16篇
  1996年   11篇
  1994年   9篇
  1993年   7篇
  1992年   14篇
  1991年   14篇
  1990年   10篇
  1989年   6篇
  1988年   8篇
  1987年   14篇
  1986年   15篇
  1985年   17篇
  1984年   10篇
  1983年   8篇
  1981年   4篇
  1980年   6篇
  1979年   9篇
  1978年   4篇
  1976年   6篇
  1975年   6篇
  1974年   8篇
  1973年   5篇
  1971年   9篇
  1968年   4篇
排序方式: 共有1667条查询结果,搜索用时 0 毫秒
81.
The knowledge and attitudes regarding infant feeding practices were studied among those health personnel (doctors, nurses and dais) who were delivering M.C.H. services in the peripheral areas of Barmer District (W. Rajasthan). The study revealed that the health personnel under study are not fully aware of the correct infant feeding practices and thus their incorrect knowledge and attitudes when put into practice can have detrimental effects. This study highlights the need of continuing medical education and stepping up of pediatric training in undergraduate courses.  相似文献   
82.
We report a case of anterior chamber Cysticercus cellulosae that was removed by viscoexpression.  相似文献   
83.
A 21-year-old male presented with sudden onset of right-sided third nerve paresis. Angiogram showed a fenestrated posterior communication artery on the right side and no other vascular anomalies. There was no other lesion that could suggest a cause for the third nerve weakness. Fenestration of the posterior communicating artery has not been reported till date. The case is discussed and the literature on the subject is reviewed.  相似文献   
84.
Amersdorfer P  Wong C  Smith T  Chen S  Deshpande S  Sheridan R  Marks JD 《Vaccine》2002,20(11-12):1640-1648
Understanding the antibody response in botulinum intoxication is important for vaccine design and passive prophylaxis. To investigate this activity, we have studied the immune response to BoNT/A (botulinum neurotoxin serotype A) binding domain (HC) at the molecular level using phage display. The scFv antibodies were isolated from V-gene repertoires prepared from (a) human volunteer immunized with pentavalent botulinum toxoid and (b) non-immune human peripheral blood lymphocytes and spleenocytes. A large panel of serotype specific phage expressing botulinum binding scFv could be selected from both libraries. Epitope mapping of immune scFv binders towards BoNT/A HC revealed surprisingly a limited number of scFv recognizing conformational epitopes that corresponded to two distinct groups, clusters I and II. Only scFv from cluster I exhibited neutralizing activity in the mouse hemidiaphragm assay. Anti- BoNT/A HC clones derived from a non-immune library could be conveniently grouped into clusters III-XI and appeared to share no overlapping epitopes with cluster I or II. In addition they showed no neutralization of toxin at biologically significant concentrations. We therefore suggest that a vaccine based on the pentavalent botulinum toxoid directs the humoral immune response to a limited number of immunodominant epitopes exposed on the binding domain HC.  相似文献   
85.
BACKGROUND AND PURPOSE: Several anatomic abnormalities of the pituitary gland have been described as occurring in association with congenital growth hormone deficiency, including hypoplasia of the adenohypophysis, truncation of the pituitary stalk, and ectopia of the neurohypophysis. Their pathogenesis, however, is obscure. Normal pituitary development is dependent on the sequential expression of a series of ontogenetic factors. Growth hormone-releasing hormone (GHRH) is known to stimulate somatotroph proliferation, and a dwarf mouse model with a mutant GHRH receptor, the "little mouse," has a small anterior pituitary due to hypoplasia of the somatotrophs. We recently described the human homolog of the little mouse (dwarfism of Sindh), caused by a homozygous nonsense mutation in the GHRH receptor gene in a Pakistani kindred. We investigated MR imaging characteristics to gain information regarding the potential role of GHRH in human pituitary organogenesis. METHODS: MR images of the head were obtained of four affected male patients (age range, 22-29 years). Maximal anterior pituitary dimensions were determined from sagittal and coronal images, and pituitary volumes were estimated from cubic and ellipsoid formulae. The measurements were compared with normative values matched for age and sex. RESULTS: The adenohypophysis was small in each of the four patients. The maximal height for the anterior pituitary was 3 mm in three patients and 2 mm in one (mean +/- SD, 2.75 +/- 0.5 mm), which is significantly (P < .001) less than the expected height of 5.6 +/- 1.0 mm for men in this age group. Estimates of anterior pituitary volume in the patients ranged from 75 to 124 mm3 (104 +/- 21 mm3), which corresponds to 35% to 52% of the normal mean volume corrected for small head size (P < .005). No other cranial abnormalities were identified. CONCLUSION: We describe significant hypoplasia of the adenohypophysis occurring in four dwarfs with a nonsense mutation in the GHRH receptor. In addition to isolated growth hormone deficiency and severe dwarfism, affected patients have anterior pituitary hypoplasia, presumably due to somatotroph maldevelopment. Resistance to GHRH explains the hypoplasia of the adenohypophysis--a feature that contributes to growth hormone deficiency in this syndrome. This is one of the few instances in which the molecular basis of pituitary dysmorphogenesis has been identified.  相似文献   
86.
We have previously demonstrated that ursodeoxycholic acid(UDCA) and a fluorinated analogue of vitamin D(3), F(6)-D(3),inhibited colonic carcinogenesis in the azoxymethane (AOM) model. Generalized colonic mucosal hyperproliferation and aberrant crypt foci (ACF) are intermediate biomarkers of colon cancer. Using these biomarkers, in this study we examined the anticarcinogenic mechanisms of these chemopreventive agents. Rats were maintained on AIN-76A chow or supplemented with 0.4% UDCA or F(6)-D(3) (2.5 nmol/kg chow) and treated weekly with AOM 20 mg i.p./kg wt or saline x 2 weeks. F(6)-D(3) was continued for an additional 2 weeks and UDCA for the duration of the study. At 40 weeks, animals received bromodeoxyuridine (BrdUrd) i.p. 2 h before sacrifice. A portion of each tumor was fixed in formalin and the remainder flash frozen. Colons were divided longitudinally and half-fixed in formalin and half in ethanol. The size and location of methylene blue-stained ACF were recorded. Cell proliferation (BrdUrd labeling) and apoptosis (terminal deoxynucleotidyl transferase-mediated nick end labeling assay) were measured in colonic crypts and tumors. Protein expression levels of several regulators of cell proliferation were analyzed by immunostaining and Western blotting. Colonic crypt cyclin D1 and E-cadherin mRNA levels were measured by real-time PCR. In saline injected controls, neither UDCA nor F(6)-D(3) alone had any effect on cytokinetic parameters or on the expression of mitogenic regulators. AOM significantly increased the proliferation (percentage of BrdUrd-positive cells) of both ACF (23.1 +/- 1.7%) and non-ACF crypts (17.6 +/- 1.6%), compared with normal colonic crypts (4.5 +/- 0.8%; P < 0.05). This hyperproliferation was accompanied by a 5-fold increase in cyclin D1 and >50% decrease in E-cadherin protein (P < 0.05) in ACF, both of which are predicted to be growth-enhancing alterations. UDCA and F(6)-D(3) significantly (P < 0.05) inhibited AOM-induced crypt cell hyperproliferation, ACF development, and tumor burden. These chemopreventive agents also significantly blocked AOM-induced alterations in cyclin D1 and E-cadherin protein in ACF and tumors. In ACF, changes in mRNA levels of cyclin D1, but not E-cadherin, paralleled alterations in protein expression. Cyclooxygenase-2 and inducible nitric oxide synthase were increased in AOM tumors but not in ACF, and these changes were blocked by UDCA and F(6)-D(3). UDCA and F(6)-D(3) significantly inhibited ACF development and hyperproliferation, in part, by preventing carcinogen-induced alterations in cyclin D1 and E-cadherin. In established tumors, UDCA and F(6)-D(3) also limited inductions of cyclooxygenase-2 and inducible nitric oxide synthase, which together with their effects on cyclin D1 and E-cadherin, contribute to their chemopreventive actions.  相似文献   
87.
88.
89.
90.
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