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   751篇
  免费   48篇
  国内免费   4篇
儿科学   14篇
妇产科学   16篇
基础医学   145篇
口腔科学   4篇
临床医学   71篇
内科学   142篇
皮肤病学   10篇
神经病学   112篇
特种医学   10篇
外科学   119篇
综合类   12篇
预防医学   42篇
眼科学   8篇
药学   47篇
中国医学   5篇
肿瘤学   46篇
  2023年   8篇
  2022年   4篇
  2021年   13篇
  2020年   4篇
  2019年   11篇
  2018年   15篇
  2017年   11篇
  2016年   12篇
  2015年   15篇
  2014年   13篇
  2013年   31篇
  2012年   35篇
  2011年   52篇
  2010年   23篇
  2009年   33篇
  2008年   44篇
  2007年   44篇
  2006年   44篇
  2005年   47篇
  2004年   37篇
  2003年   42篇
  2002年   28篇
  2001年   4篇
  2000年   7篇
  1999年   9篇
  1998年   4篇
  1997年   13篇
  1996年   6篇
  1995年   8篇
  1994年   7篇
  1993年   13篇
  1992年   10篇
  1991年   8篇
  1990年   4篇
  1989年   17篇
  1988年   10篇
  1987年   14篇
  1986年   6篇
  1984年   12篇
  1983年   8篇
  1982年   6篇
  1981年   10篇
  1980年   5篇
  1979年   6篇
  1978年   5篇
  1975年   10篇
  1973年   4篇
  1969年   5篇
  1966年   4篇
  1960年   3篇
排序方式: 共有803条查询结果,搜索用时 15 毫秒
1.
2.
Many health-related research studies among Seventh-day Adventists (SDA) were published since 1958. Californian and Norwegian studies have shown that SDA have lower coronary mortality rates than the general population. This finding is usually attributed to the lifestyle advocated by the Seventh-day Adventist church with greater physical activity, lower median BMI, abstention from use of alcohol and tobacco, food habits characterized by a large intake of fruits, vegetables, cereal fiber, unsaturated fatty acids and a low consumption of saturated fats. The results about cancer incidence were discussed. Californian studies have shown significantly decreased relative risk in SDA than in the general population. Japanese studies have also reported lower risk of cancers in men with lifestyles similar to those of SDA. By contrast the Norwegian study of SDA has shown that the risk of cancer seems to be similar to that of the general population. Some studies reported a greater prevalence of type 2 diabetes in the non vegetarian SDA than the vegetarian. Compared with vegetarian, non vegetarian SDA reported more medication use, more chronic diseases, more hospitalizations and surgeries. Lifestyle choices of SDA as above described could prevent a great many coronary artery disease and type 2 diabetes. This lifestyle is now emphasized by French PNNS.  相似文献   
3.
Ordinary surgical rubber gloves are penetrated by methylmethacrylate monomer (MMA) in less than 1 minute, as demonstrated by gas chromatographic measurements. A three-layered PVP glove, 0.07 mm thick - consisting of an outer layer of polyethylene, an intermediary layer of ethylene vinyl alcohol copolymer, and an inner layer of polyethylene - was impervious for 20 minutes, whereas a viton-butyl rubber glove, 0.27 mm thick, was impervious for 15 minutes.

The PVP glove is recommended to orthopedic surgeons, nurses, and other handling acrylic bone cements to avoid sensitization, and is especially recommended to persons with known contact allergy to MMA.  相似文献   
4.
Androgens are important regulators of bone and prostate health in elderly men. The role of serum levels of glucuronidated androgen metabolites as predictors of BMD and prostate volume in men is unclear. We show that specific glucuronidated androgen metabolites predict BMD and prostate volume in elderly men. INTRODUCTION: Androgens are important regulators of bone and prostate health in elderly men. Local synthesis and degradation of androgens are likely to be important parameters of biological action of androgens in androgen-responsive tissues. The aim of this study was to determine the role of serum levels of glucuronidated androgen metabolites as predictors of BMD and prostate volume in elderly men. MATERIALS AND METHODS: A subsample of the population-based Swedish part of the MrOS study (n = 631, average age = 75.9 years) was investigated. Bone parameters were measured using DXA. Serum levels of total testosterone (T) and dihydrotestosterone (DHT) were measured by gas chromatography/mass spectroscopy (GC-MS); androstane-3alpha,17beta-diol-3glucuronide (3G) and androstane-3alpha,17beta-diol-17glucuronide (17G) were measured by liquid chromatography/mass spectroscopy. Prostate volume (n = 159) was measured by transrectal ultrasound. RESULTS: The general pattern is that two of the glucuronidated androgen metabolites, namely 17G and 3G, are stronger positive predictors of BMD than the bioactive androgens (T and DHT). In addition, 17G is a clear positive predictor of prostate volume, explaining 4.5% of the variance in prostate volume, whereas the bioactive androgens do not display any association with prostate volume. CONCLUSIONS: Serum levels of specific glucuronidated androgen metabolites predict BMD and prostate volume in elderly men. Future studies should determine if the glucuronidated androgen metabolites also reflect other biological correlates of androgenic activity, including prostate cancer, and if low levels might be a marker of general androgen deficiency in men.  相似文献   
5.
6.
Mainly through the transformation of dehydroepiandrosterone (DHEA) into androgens in peripheral tissues by intracrine mechanisms, women synthesize at least two-thirds of the androgens found in men. Such data strongly suggest that androgens exert very important but so far underestimated physiological functions in women, including in the breast. In fact, the mammary gland possesses all the enzymatic machinery required to transform DHEA into both androgens and estrogens, although androgens are the predominant steroids synthesized from DHEA in the mammary gland. Early clinical studies have shown beneficial effects of androgens on breast cancer which are comparable to those observed with other hormonal therapies. In fact, a long series of preclinical and clinical data clearly indicate that proliferation of both the normal mammary gland and breast cancer results from the balance between the stimulatory effect of estrogens and the inhibitory effect of androgens. Moreover, the data showing the additive inhibitory effects of antiestrogens and androgens suggest that taking advantage of the inhibitory effect of androgens on breast cancer proliferation could well improve the efficacy of the currently used estrogen deprivation therapies for the treatment and prevention of breast cancer, the best and most physiological candidate being DHEA that limits the androgenic exposure to the tissues which possess the required enzymatic intracrine machinery.  相似文献   
7.
Studies in normal man and rodents have demonstrated that the expression of the dominant glucose transporter in skeletal muscle, GLUT4, is regulated by insulin at supraphysiological circulating levels. The present study was designed to determine whether intensified insulin replacement therapy for 24 h given to patients with Type 1 diabetes in poor metabolic control was associated with an adaptive regulation of GLUT4 mRNA and protein levels in vastus lateralis muscle. Nine Type 1 diabetic patients with a mean HbA1c of 10.3% were included in the protocol. After intensified treatment with soluble insulin for 24 h the fasting plasma glucose concentration decreased from 20.8 ± 2.3 (SD) to 8.7 ± 2.3 mmol 1?1 whereas the fasting serum insulin level increased from 0.06 ± 0.02 to 0.17 ± 0.09 nmol 1?1 However, despite a 2.8-fold increase in serum insulin levels and more than a halving of the plasma glucose concentration for at least 15 h no significant alterations occurred in the amount of GLUT4 protein (0.138 ± 0.056, poor control vs 0.113 ± 0.026 arb. units, improved control, p = 0.16) or GLUT4 mRNA (96432 ± 44985, poor control vs 81395 ± 25461 arb. units, improved control, p = 0.54). These results suggest, that in spite of evidence that high insulin levels affect GLUT4 expression in muscle, changes in serum insulin within the physiological range do not play a major role in the short-term regulation of GLUT4 expression in Type 1 diabetic patients.  相似文献   
8.
Summary Shortly after subcutaneous or intraperitoneal injection of nontoxic quantities of trypan blue into laying Japanese quails, red fluorescent yolk granules appear in the peripheral ooplasm of their oocytes at the end of the lampbrush stage or subsequently. Later a red fluorescence can be observed in the apical cytoplasm of the granulosa cells. The results obtained by this method confirm our previous results (Callebaut 1974) obtained by autoradiography after 3H-leucine administration and furnish interesting additional data. The trypan blue-induced fluorescence method gives a good indication of the permeability of the oocytal cortex and its derivative the germinal disc. The avian yolk which is, or has been peripherally assembled (primordial, true white and yellow yolk) can be characteristically labelled by the administration of trypan blue. The injection of higher, still nontoxic quantities of trypan blue has a prolonged retarding effect and permits the marking of a broader part of the germinal disc or eventually of the blastoderm which develops from it.  相似文献   
9.
Cystic fibrosis (CF) is an autosomal recessive disorder with a prevalence at birth estimated at 1/2000-1/2500 livebirths in Caucasian populations. Some 127 CF individuals are known in Saguenay-Lac-St-Jean (SLSJ), a geographically isolated region of Quebec. The prevalence at birth was estimated at 1/902 live borns, and the carrier rate was estimated at 1/15 inhabitants in the SLSJ region. The mean inbreeding coefficient was only slightly elevated in the CF group compared with three control groups, and was due to remote consanguinity. The mean kinship coefficient was 2.4 times higher in the CF group than in the control groups. In SLSJ region, the places of origin of the CF individuals and their parents did not show a clustered nonuniform distribution. Endogamy was not higher in the CF group than in control groups.  相似文献   
10.
Needle puncture and other accidents that occur during surgery and other procedures may lead to viral infections of medical personnel, notably by hepatitis C (HCV) and human immunodeficiency virus (HIV), now that hepatitis B can be prevented by vaccination. A new surgical glove called G-VIR, which contains a disinfecting agent for enveloped viruses, has been developed. Herpes simplex type 1 (HSV) was used as a standard enveloped virus in both in vitro and in vivo tests of the virucidal capacity of the glove. Bovine viral diarrhea virus (BVDV) and feline immunodeficiency virus (FIV) were used as models for HCV and HIV, respectively. For in vitro study, a contaminated needle was passed through a glove and residual virus was titrated; for in vivo studies, animals were stuck with a contaminated needle through a glove. Despite variation in virus enumeration inherent in the puncture technique, statistical evaluation showed that infection was reproducibly and substantially reduced by passage through the virucidal layer. For BVDV, the amount of virus passing through the virucidal glove was reduced in 82% of pairwise comparisons with control gloves that lacked the virucidal agent; when plaque counts were adjusted to a common dilution, the median count for the virucidal glove was on the average reduced >10-fold. In experiments in which the proportion of wells infected with FIV was measured, the ratio of TCID(50) values (control glove to G-VIR) was >15, and probably much higher. For HSV, the amount of virus passing through the virucidal glove was reduced in 81% of comparisons with control gloves; the median of adjusted plaque counts was reduced on the average approximately eightfold or ninefold. In vivo tests with FIV and HSV in cats and mice, respectively, found smaller percentage reductions in infection than the in vitro tests but confirmed the virucidal effect of the gloves.  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