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   3245篇
  免费   236篇
  国内免费   14篇
耳鼻咽喉   43篇
儿科学   57篇
妇产科学   76篇
基础医学   479篇
口腔科学   49篇
临床医学   301篇
内科学   647篇
皮肤病学   74篇
神经病学   180篇
特种医学   155篇
外科学   607篇
综合类   40篇
一般理论   2篇
预防医学   197篇
眼科学   86篇
药学   196篇
中国医学   2篇
肿瘤学   304篇
  2024年   7篇
  2023年   29篇
  2022年   46篇
  2021年   105篇
  2020年   75篇
  2019年   112篇
  2018年   115篇
  2017年   73篇
  2016年   70篇
  2015年   110篇
  2014年   126篇
  2013年   193篇
  2012年   244篇
  2011年   255篇
  2010年   181篇
  2009年   136篇
  2008年   203篇
  2007年   196篇
  2006年   193篇
  2005年   183篇
  2004年   182篇
  2003年   155篇
  2002年   121篇
  2001年   21篇
  2000年   27篇
  1999年   33篇
  1998年   23篇
  1997年   18篇
  1996年   14篇
  1995年   19篇
  1994年   13篇
  1993年   19篇
  1992年   12篇
  1991年   22篇
  1990年   12篇
  1989年   11篇
  1988年   15篇
  1987年   13篇
  1986年   10篇
  1985年   18篇
  1984年   11篇
  1983年   15篇
  1982年   3篇
  1981年   8篇
  1980年   8篇
  1979年   3篇
  1978年   8篇
  1976年   8篇
  1975年   3篇
  1964年   3篇
排序方式: 共有3495条查询结果,搜索用时 0 毫秒
1.
2.
Graefe's Archive for Clinical and Experimental Ophthalmology - To evaluate the long-term safety and efficacy of intrastromal bevacizumab for treatment of deep corneal neovascularization in...  相似文献   
3.
4.
The bed nucleus of the stria terminalis (BNST) and its adrenergic input are key components in stress-induced reinstatement and maintenance of drug use. Intra-BNST injections of either beta-adrenergic receptor (beta-AR) antagonists or alpha2-adrenergic receptor (alpha2-AR) agonists can inhibit footshock-induced reinstatement and maintenance of cocaine- and morphine-seeking. Using electrophysiological recording methods in an in vitro slice preparation from C57/Bl6j adult male mouse BNST, we have examined the effects of adrenergic receptor activation on excitatory synaptic transmission in the lateral dorsal supracommissural BNST (dBNST) and subcommissural BNST (vBNST). Alpha2-AR activation via UK-14,304 (10 microM) results in a decrease in excitatory transmission in both dBNST and vBNST, an effect predominantly dependent upon the alpha2A-AR subtype. Beta-AR activation via isoproterenol (1 microM) results in an increase in excitatory transmission in dBNST, but not in vBNST. Consistent with the work with receptor subtype specific agonists, application of the endogenous ligand norepinephrine (NE, 100 microM) elicits two distinct effects on glutamatergic transmission. In dBNST, NE elicits an increase in transmission (62% of dBNST NE experiments) or a decrease in transmission (38% of dBNST NE experiments). In vBNST, NE elicits a decrease in transmission in 100% of the experiments. In dBNST, the NE-induced increase in synaptic transmission is blocked by beta1/beta2- and beta2-, but not beta1-specific antagonists. In addition, this increase is also reduced by the alpha2-AR antagonist yohimbine and is absent in the alpha2A-AR knockout mouse. In vBNST, the NE-induced decrease in synaptic transmission is markedly reduced in the alpha2A-AR knockout mouse. Further experiments demonstrate that the actions of NE on glutamatergic transmission can be correlated with beta-AR function.  相似文献   
5.
PURPOSE: This study aims to determine the effect of loss of breast cancer metastasis suppressor 1 (BRMS1) protein expression on disease-free survival in breast cancer patients stratified by estrogen receptor (ER), progesterone receptor (PR), or HER2 status, and to determine whether loss of BRMS1 protein expression correlated with genomic copy number changes. EXPERIMENTAL DESIGN: A tissue microarray immunohistochemical analysis was done on tumors of 238 newly diagnosed breast cancer patients who underwent surgery at the Cleveland Clinic between January 1, 1995 and December 31, 1996, and a comparison was made with 5-year clinical follow-up data. Genomic copy number changes were determined by array-based comparative genomic hybridization in 47 breast cancer cases from this population and compared with BRMS1 staining. RESULTS: BRMS1 protein expression was lost in nearly 25% of cases. Patients with tumors that were PR negative (P=0.006) or HER2 positive (P=0.039) and <50 years old at diagnosis (P=0.02) were more likely to be BRMS1 negative. No overall correlation between BRMS1 staining and disease-free survival was observed. A significant correlation, however, was seen between loss of BRMS1 protein expression and reduced disease-free survival when stratified by either loss of ER (P=0.008) or PR (P=0.029) or HER2 overexpression (P=0.026). Overall, there was poor correlation between BRMS1 protein staining and copy number status. CONCLUSIONS: These data suggest a mechanistic relationship between BRMS1 expression, hormone receptor status, and HER2 growth factor. BRMS1 staining could potentially be used in patient stratification in conjunction with other prognostic markers. Further, mechanisms other than genomic deletion account for loss of BRMS1 gene expression in breast tumors.  相似文献   
6.
A high resolution screening (HRS) technology is described, in which gradient high-performance liquid chromatography (HPLC) is connected on-line to three parallel placed bioaffinity detection systems containing mammalian cytochromes P450 (P450s). The three so-called enzyme affinity detection (EAD) systems contained, respectively, liver microsomes from rats induced by beta-naphthoflavone (CYP1A activity), phenobarbital (CYP2B activity), and dexamethasone (CYP3A activity). Each P450-EAD system was optimized for enzyme, substrate, and organic modifier (isopropyl alcohol, methanol, and acetonitrile) in flow injection analysis mode. Characteristic P450 ligands were used to validate the P450-EAD systems. IC(50) values of the ligands were measured and found to be similar to those obtained with conventional microtiter plate reader assays. Detection limits (n = 3; signal-to-noise ratio = 3) of potent inhibitors ranged from 1 to 3 pmol for CYP1A activity, 4 to 17 pmol for CYP2B activity, and 4 to 15 pmol for CYP3A activity. The three optimized P450-EAD systems were subsequently coupled to gradient HPLC and used to screen compound mixtures for individual ligands. Finally, to increase analysis efficiency, a HRS system was constructed in which all three P450-EAD systems were coupled on-line and in parallel to gradient HPLC. The triple parallelized P450-EAD system was shown to enable rapid profiling of individual components in complex mixtures for inhibitory activity to three different P450s.  相似文献   
7.
A model of posterior urethral valves in fetal lambs was developed in order to evaluate the effect of intrauterine urinary obstruction on the developing kidney. Complete urethral obstruction was induced in five fetal lambs at 43 to 45 days of gestation. Two control fetal lambs underwent sham operations. At full term (140 days), two of the five experimental lambs and both control lambs were available for postmortem examination. Results of gross and histological examination of the control lambs were normal. In contrast, the kidneys of the experimental lambs were markedly asymmetrical in size. Histological examination of the kidneys in experimental lambs showed cystic dilatation of the collecting ducts and occasional cystic dilatation of Bowman's spaces, features compatible with obstruction. Also noted were peripheral cortical cysts and primitive tubules lined with cuboidal epithelium and surrounded by fibromuscular collarettes, characteristic of renal dysplasia. One of the infant lambs had many characteristics of the prune-belly syndrome, including a wrinkled, markedly distended abdomen, deficient abdominal wall musculature, flared chest wall, limb deformities, and undescended testes. These results suggest that early in utero urethral obstruction (at the beginning of the second third of gestation) causes renal dysplasia. The results also support the hypothesis that the prune-belly syndrome results from abdominal distention that occurs early in gestation.  相似文献   
8.
9.
Epidermoid cyst (monodermal teratoma) of the testis   总被引:3,自引:0,他引:3  
We report 14 patients with epidermoid cyst of the testis (monodermal teratoma). In 7 patients (5 treated within the last 5 years) the mass was excised and adjacent testicular tissue was biopsied. Seven patients underwent radical inguinal orchiectomy. Carcinoma in situ was not detected in any testicular tissue examined. There was no evidence of tumour recurrence in any patient after a mean follow-up of 10 years. Ultrasonographic appearance was not specific for a diagnosis of epidermoid cyst and exploratory surgery was required in all cases. Excision of the tumour and biopsy of adjacent testicular tissue to determine the presence or absence of carcinoma in situ is adequate treatment for this rare testicular neoplasm.  相似文献   
10.
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