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   3349篇
  免费   176篇
  国内免费   10篇
耳鼻咽喉   40篇
儿科学   156篇
妇产科学   46篇
基础医学   434篇
口腔科学   33篇
临床医学   192篇
内科学   511篇
皮肤病学   52篇
神经病学   235篇
特种医学   87篇
外科学   434篇
综合类   86篇
预防医学   193篇
眼科学   171篇
药学   447篇
中国医学   43篇
肿瘤学   375篇
  2023年   25篇
  2022年   53篇
  2021年   106篇
  2020年   57篇
  2019年   70篇
  2018年   98篇
  2017年   64篇
  2016年   93篇
  2015年   85篇
  2014年   100篇
  2013年   149篇
  2012年   239篇
  2011年   244篇
  2010年   151篇
  2009年   129篇
  2008年   179篇
  2007年   169篇
  2006年   153篇
  2005年   152篇
  2004年   133篇
  2003年   106篇
  2002年   90篇
  2001年   50篇
  2000年   66篇
  1999年   53篇
  1998年   30篇
  1997年   19篇
  1996年   23篇
  1995年   21篇
  1994年   20篇
  1993年   18篇
  1992年   46篇
  1991年   43篇
  1990年   35篇
  1989年   55篇
  1988年   45篇
  1987年   37篇
  1986年   32篇
  1985年   31篇
  1984年   28篇
  1983年   27篇
  1982年   15篇
  1981年   16篇
  1979年   34篇
  1978年   15篇
  1976年   14篇
  1974年   10篇
  1973年   15篇
  1972年   14篇
  1970年   10篇
排序方式: 共有3535条查询结果,搜索用时 15 毫秒
31.

Textile dyes are becoming a growing threat to the environment. This report presents the findings of the study on the toxicity of the textile dye Alizarin Red S on two freshwater microalgae. The acute toxicity assay revealed that 96-h EC50 values of Chlorella vulgaris and Spirulina platensis were 29.81 mg/L and 18.94 mg/L respectively. The pigments chlorophyll-a, b and carotenoids in C. vulgaris on 96-h exposure to the dye were 2.91, 3.29 and 3.01 times lower in analogy to control whereas Spirulina platensis showed 2.89and 2.56 fold decrease in chlorophyll-a and carotenoid content than control. After the test period of 96-h with dye, the protein content of C. vulgaris and S. platensis were 2.33 and 1.77 times lower compared to the control. The growth inhibition rate, pigment as well as the protein content declined in compliance with the rise in dye concentration, which anticipate paradigm about the toxic effects of the textile dye.

  相似文献   
32.
Episodic Vertigo Comprises a large group of patients seen in any neurootology unit. A total of 118 subjects were reviewed who attended the neurootology unit. Vertigo of shorter duration was noted in 78 and of longer duration in 40 cases. 51 cases showed bilateral neurosensory deafness, 15 cases had bilateral and another one case had unilateral conductive loss. Spinovestibular tests were abnormal in all cases of vertigo of short duration but only 29 cases showed abnormal reflex in patients with a long duration of illness. Thermal vestibulometry revealed hyporeflexia in 33 cases, directional preponderance in 30 cases and 4 cases showed hyperreflexia 28 cases had peripheral lesions while 81 cases had central lesions. The acute cases showed significant improvement on follow up except cases with abnormality in thermal vestibulometry . The cases with positional nystagmus showed improvement with head and body balance exercises expect in those who received treatment with vestibulosedative and vestibular suppersive drugs. Hearing loss remained the same except in patients with middle ear disorders.  相似文献   
33.
Craniofacial osteogenic sarcomas are rare primary malignant bone tumors and very few cases involving zygomatic bone were reported in literature. We present our experience of multimodality management of a case of primary osteogenic sarcoma of zygoma. Wide radical excision of the tumor including the parotid gland was done followed by three cycles of adjuvant chemotherapy and fifty Gy of external radiotherapy. The patient is disease-free at two years follow-up. Till 1970s, craniofacial osteogenic sarcomas were managed mainly by radical surgery with a high local failure rate. With the advances made in the field of radiotherapy and chemotherapy, multimodality therapy is playing a major role in the treatment of these aggressive tumors with better overall and disease-free survival.  相似文献   
34.
Cases of reduced uptake of pertechnetate-99m ion in the thyroid gland due to the presence, in the injected solution, of aluminium species at concentrations higher than 4 g/cm3 are reported. This inconvenience can be avoided either by injecting chromatographically pure pertechnetate-99m ion or by allowing the eluate of high aluminium content to stand for about 4 h.  相似文献   
35.
36.
37.
Together with thyroid cancer, cancer of the gallbladder is the only non-sex hormone-related cancer displaying a female preponderance, with incidence being 3-4 times more common among women. We carried out this study to evaluate the role of menstrual, reproductive and lifestyle factors in gallbladder carcinogenesis. A case-control study involving 64 newly diagnosed cases of gallbladder cancer and 101 cases of cholelithiasis was carried out. A detailed menstrual and reproductive history was illustrated beside detailed lifestyle history, in particular consumption of betel nut, tobacco and alcohol and smoking, odds ratio was calculated. Mean age of the patients with cancer was 51+/-1.2 years while it was 40.9+/-1.2 years for gallstones; 69% of cancer patients and 90% of gallstones patients were females. More than half of the cancer patients (53%) and 43% of the gallstone patients were illiterate. A past history of typhoid was present in 22% of cancer patients and 13% of gallstone patients, while 35% of cancer and 25% of gallstone patients were chewers, 18.1 and 9.9% were smokers, and 10% of cancer and 2% of gallstone patients consumed alcohol. Mean age of menarche was 13.4+/-1.2 years among female patients with cancer while it was 14.0+/-1.4 years for gallstone patients. Higher age at menarche (>13 years, OR 2.48, 95% confidence interval (CI) 1.16-5.3), higher number of childbirths(>3 births, OR 3.92; 95% CI 1.4-10.3), higher number of pregnancies (>3 pregnancies, OR 6.66, 95% CI 1.8-23.4), and higher age at last childbirth (>25 years, OR 2.97, 95% CI 1.04-8.5) were found to have significantly higher risk of developing gallbladder cancer. In conclusion, tobacco chewing and smoking are associated with increased odds of gallbladder cancer. Similarly early menarche, late menopause, multiple pregnancies and childbirth increased the risk of gallbladder cancer.  相似文献   
38.
In the present investigations,the antitumorigenic effect of black tea polyhenols(BTP)in two-stage mouse skin model of carcinogenesis was studied.The animals were initated with a single“subcarcinogenic”topical dose(52μg/200μl acetone)of 7,12-dimethylbenzanthracene(DMBA).To evaluate the anti-tumour initiating activity,BTP was topically appied twice a week for three weeks prior to DMBA applications,followed by topical treatment with 12-o-tetradecanoyl phorbol-13-acetate(TPA)(5μg/200μl acetone,2x/wk.)as promoter.For eveluation of antitumor prmotin activity,BTP was applied prior to each treatment of TPA.BTP application showed marked inhibitory effect as antitumour initiator as well as antitumour promoter in mouse skin model o two-stage carcinogenesis.Since initiation involves genetic pathway and tumour prmotion involves epigenetic pathway,it seems that BTP exerts its antitumorigenic effect by altering both genetic and epigenetic pathways.  相似文献   
39.
40.
OBJECTIVES: Urinary bladder hypertrophy and hyperplasia are common features of bladder outlet obstruction (BOO). The urinary bladder is known to synthesize endothelin-1 (ET-1), which is a potent vasoconstrictor peptide with mitogenic properties. Using an animal model of partial BOO, we investigated the potential role of ET-1 and its receptor subtypes (ET(A) and ET(B)) in bladder smooth muscle cell (SMC) proliferation. MATERIALS AND METHODS: Partial BOO was produced in adult male New Zealand White rabbits. After 3 weeks, the bladder was removed and SMCs from the dome and bladder neck were grown using standard explant methodology. At passage 2, the cells were made quiescent and then further incubated in foetal calf serum (FCS), control age-matched rabbit serum (CRS) or partial BOO serum (BRS) in the presence or absence of ET(A)-antagonist (BQ123) or ET(B)-antagonist (BQ788). SMC proliferation was then measured 24 h later with 5-bromo-2'deoxy-uracil and by cell counting using a haemocytometer at 48 h. Immunostaining for alpha-actin was performed on detrusor and bladder neck cells to confirm the presence of smooth muscle cells. RESULTS: BQ123 and BQ788 did not influence detrusor or bladder neck SMC proliferation in FCS or CRS. However, in the presence of BRS, BQ123 and BQ788 (100 nmol/L) significantly (p = 0.008) inhibited detrusor and bladder neck SMC proliferation. Cell counts were significantly reduced from the detrusor (p = 0.03, p = 0.01 with BQ123 and BQ788, respectively) and bladder neck (p = 0.01 for both BQ123 and BQ78). CONCLUSIONS: These results suggest that ET antagonists may have a role in preventing SMC hyperplasia associated with partial BOO.  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