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   2245篇
  免费   114篇
  国内免费   19篇
耳鼻咽喉   53篇
儿科学   60篇
妇产科学   48篇
基础医学   216篇
口腔科学   100篇
临床医学   183篇
内科学   521篇
皮肤病学   32篇
神经病学   130篇
特种医学   47篇
外科学   403篇
综合类   61篇
一般理论   2篇
预防医学   121篇
眼科学   65篇
药学   169篇
中国医学   11篇
肿瘤学   156篇
  2023年   18篇
  2022年   36篇
  2021年   89篇
  2020年   48篇
  2019年   70篇
  2018年   94篇
  2017年   59篇
  2016年   71篇
  2015年   77篇
  2014年   85篇
  2013年   106篇
  2012年   174篇
  2011年   172篇
  2010年   94篇
  2009年   75篇
  2008年   147篇
  2007年   130篇
  2006年   116篇
  2005年   132篇
  2004年   104篇
  2003年   102篇
  2002年   86篇
  2001年   35篇
  2000年   17篇
  1999年   30篇
  1998年   12篇
  1997年   12篇
  1996年   11篇
  1995年   12篇
  1994年   15篇
  1993年   4篇
  1992年   13篇
  1991年   5篇
  1990年   10篇
  1989年   6篇
  1988年   9篇
  1987年   8篇
  1986年   8篇
  1985年   4篇
  1984年   7篇
  1982年   8篇
  1981年   8篇
  1980年   6篇
  1979年   5篇
  1976年   4篇
  1974年   4篇
  1971年   5篇
  1970年   8篇
  1969年   5篇
  1968年   4篇
排序方式: 共有2378条查询结果,搜索用时 31 毫秒
121.
Cellular microtubules, polymers of tubulin, alternate relentlessly between phases of growth and shortening. We now show that noscapine, a tubulin-binding agent, increases the time that cellular microtubules spend idle in a paused state. As a result, most mammalian cell types observed arrest in mitosis in the presence of noscapine. We demonstrate that noscapine-treated murine melanoma B16LS9 cells do not arrest in mitosis but rather become polyploid followed by cell death, whereas primary melanocytes reversibly arrest in mitosis and resume a normal cell cycle after noscapine removal. Furthermore, in a syngeneic murine model of established s.c. melanoma, noscapine treatment resulted in an 85% inhibition of tumor volume on day 17 when delivered by gavage compared with untreated animals (P 相似文献   
122.
PURPOSE: The authors present a prospective study on 10 patients with stereotactic infusion of tissue plasminogen activator (rtPA) intraparenchimal hemorrhage. METHODS: Between 1999 and 2000, 10 patients with deep seated hematomas in the basal ganglia were selected for stereotactic infusion of rtPA and spontaneous clot drainage. RESULTS: All cases had about 80% reduction of the hematoma volume in the CT scan at the third day. The intracranial pressure was normalized by the third day too. There were no local or systemic complications with the use of this thrombolytic. The results were shown by the Glasgow Outcome Scale with six patients in V, three in IV and one in III after 3 months. CONCLUSION: Early treatment and drainage with minimally invasive neurosurgery, can make these patients with deep-seated hematomas recover the consciousness and they can be rehabilitated earlier avoiding secondary complications.  相似文献   
123.
124.
125.
126.

Background  

An observational case series was used to study the virulence characteristics and genotypes of paired Staphylococcus epidermidis isolates cultured from intraocular samples and from periocular environment of patients with postcataract surgery endophthalmitis.  相似文献   
127.

Background  

We describe corneal endothelial cell density and morphology in normal Iranian eyes and compare endothelial cell characteristics in the Iranian population with data available in the literature for American and Indian populations.  相似文献   
128.
Previous studies have shown that Rhodamine 123 (Rh123) is an efficient tumor targeting agent for argon laser photodynamic therapy in vitro. Effectiveness of this approach for cancer treatment in vivo will depend on Rh123 tumor uptake kinetics and laser energy delivery via fiberoptics to the tumor site. In the present study, tumor and normal cells were exposed in vitro to 1 μg/mL Rh123 until 10%, 50%, and 100% of maximum uptake was achieved. Laser treatment response was monitored by trypan blue exclusion for tumor cell viability and by MTT tetrazolium assays to measure mitochondrial dehydrogenase activity. TE671 fibrosarcoma cells were highly sensitive to argon laser phototherapy (514 nm, 5 W, 1 minute, Tmax = 8°C), with mitochondrial inhibition seen after Rh123 uptake of 12, 50, and 100 ng/million cells. P3 squamous cell carcinoma cells were inhibited 20% and 75% by the laser after Rh123 uptake of 13 or 30 ng/million cells, respectively. M26 melanoma cells were not sensitive to the laser after 15 ng/million cells Rh123 uptake but were inhibited 45% and 75% after Rh123 uptake of 80 and 160 ng/million cells. Micro2 fibroblast mitochondrial activity was reduced less than 25% by the laser after Rh123 uptake of 50 ng/million cells. Cell viability after maximum Rh123 uptake and laser treatment was decreased to 30%, 15%, and 2% for M26 melanoma, P3 squamous cell carcinoma, and TE671 fibrosarcoma cells, but remained over 80% for Micro2 fibroblasts. The results suggest that Rh123 laser treatment response depends on tumor type and drug uptake level, with normal cells being much less sensitive to phototherapy.  相似文献   
129.
In recent years, significant effort has been made to identify genes that influence breast cancer risk. Because the high-penetrance breast cancer susceptibility genes BRCA1 and 2 play a role only in a small fraction of breast cancer cases, understanding the genetic risk of the majority of breast cancers will require the identification and analysis of several lower penetrance genes. The estrogen-signaling pathway plays a crucial role in the pathophysiology of breast cancer; therefore, polymorphism in genes involved in this pathway is likely to influence breast cancer risk. Our detailed analysis of gene expression profiles of estrogen- and 4-OH-tamoxifen-treated ZR75-1 breast cancer cells identified members of the sulfotransferase 1A (SULT1A) phenol sulfotransferase family as downstream targets of tamoxifen. On the basis of the induction of SULT1A by 4-OH-tamoxifen and the known inherited variability in SULT1A enzymatic activity, we hypothesized that polymorphism in sulfotransferase genes might influence the risk of breast cancer. Using an RFLP that distinguishes an arginine to histidine change in exon 7 of the SULT1A1 gene, we characterized SULT1A1 genotypes in relation to breast cancer risk. An analysis of 444 breast cancer patients and 227 controls revealed no effect of SULT1A1 genotype on the risk of breast cancer (P = 0.69); however, it did appear to influence the age of onset among early-onset affected patients (P = 0.04). Moreover, individuals with the higher activity SULT1A1*1 allele were more likely to have other tumors in addition to breast cancer (P = 0.004; odds ratio, 3.02; 95% confidence interval, 1.32, 8.09). The large number of environmental mutagens and carcinogens activated by sulfotransferases and the high frequency of the SULT1A1*1 allele in human populations warrants additional studies to address the role of SULT genes in human cancer.  相似文献   
130.
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