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   12441篇
  免费   581篇
  国内免费   63篇
耳鼻咽喉   86篇
儿科学   300篇
妇产科学   123篇
基础医学   1518篇
口腔科学   293篇
临床医学   782篇
内科学   3463篇
皮肤病学   171篇
神经病学   1063篇
特种医学   583篇
外科学   2009篇
综合类   36篇
一般理论   1篇
预防医学   410篇
眼科学   138篇
药学   785篇
中国医学   50篇
肿瘤学   1274篇
  2023年   73篇
  2022年   120篇
  2021年   191篇
  2020年   120篇
  2019年   184篇
  2018年   212篇
  2017年   187篇
  2016年   218篇
  2015年   205篇
  2014年   278篇
  2013年   386篇
  2012年   565篇
  2011年   654篇
  2010年   345篇
  2009年   328篇
  2008年   539篇
  2007年   631篇
  2006年   623篇
  2005年   724篇
  2004年   690篇
  2003年   704篇
  2002年   747篇
  2001年   306篇
  2000年   327篇
  1999年   306篇
  1998年   229篇
  1997年   166篇
  1996年   148篇
  1995年   150篇
  1994年   153篇
  1993年   140篇
  1992年   256篇
  1991年   203篇
  1990年   220篇
  1989年   236篇
  1988年   195篇
  1987年   178篇
  1986年   175篇
  1985年   156篇
  1984年   111篇
  1983年   76篇
  1982年   58篇
  1981年   35篇
  1980年   44篇
  1979年   64篇
  1978年   38篇
  1977年   37篇
  1975年   41篇
  1974年   36篇
  1973年   38篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
The effects of dietary protein restriction on skeletal muscle fibers were studied according to morphological and biochemical approaches. Protein and DNA content of quadriceps muscles from young adult rats were decreased by the low protein and protein-free diet. Morphological examination demonstrated that there was a significant decrease in the size of muscle fibers without change in their numbers due to protein restriction. The protein/DNA ratio, accepted as an index of cell size in biochemical approaches, was compared with cell size on photomicrographs. Actual fiber size appeared much smaller than that indicated by the protein/DNA ratio.  相似文献   
42.
The author analyzed codon 347 of the rhodopsin gene using PCR (polymerase chain reaction) amplification and restriction enzymes in 19 unrelated Japanese families including 28 patients with autosomal dominant retinitis pigmentosa (ADRP). An allele of codon 347 mutation was found in a family (father and daughter). Sequence analysis shows that the mutation is from CCG to CTG. This mutation appears to be the cause of one form of ADRP, since it was also found in Japanese cases of ADRP which have a different racial background from families reported by Dryja et al.  相似文献   
43.
44.
Summary To study the effects of family history and reproductive, anthropometric, and dietary factors on the risk of breast cancer among low risk populations, we conducted a hospital-based case-control study involving 908 patients with breast cancer and their matched controls, in Japan. A positive family history of breast cancer significantly increased the risk of breast cancer (odds ratio = 1.52, 95% confidence interval: 1.14–2.03). The risk further increased with increasing number of family members affected. Obesity, single marital status, fewer births, a late childbirth, and less consumption of green-yellow vegetables and dairy products were also associated with an increased risk of breast cancer. These associations were independent in multivariate analyses. There was no increase in risk associated with consumption of high fat foods. When analyzed by menopausal status, the association with family history of breast cancer, especially in the first degree of relatives, was more evident for premenopausal breast cancer. The associations with obesity and lower consumption of dairy products were more pronounced for postmenopausal breast cancer, while those with lower parity and single marital status were stronger for premenopausal breast cancer.  相似文献   
45.
We report an unusual case of a large inferior mesenteric-caval shunt in a 25-year-old man without cirrhosis with hypoproteinemia and hypochromic anemia. In this large shunt the direct communication was between the inferior mesenteric vein and the internal iliac vein. Hemodynamic change as a result of the shunt was thought to cause his present clinical problems and future portosystemic encephalopathy. Percutaneous transcatheter embolization of the shunt with fibrin glue was performed through the internal iliac vein, and this offered amelioration of hypoproteinemia and reduction of serum ammonia levels without any complications. An interventional radiologic approach instead of surgical ligation should be attempted for portosystemic shunts, and fibrin glue, as well as coils or a detachable balloon, is also valuable as an embolizing material.  相似文献   
46.
The results of repairing cleft lip by aesthetic plastic surgery are now excellent. However, the cleft lipnose deformity is still very difficult to repair with the present techniques. A technique that can repair the cleft lip-nose deformity with good results is presented. The technique is divided into three parts: Part I consists of nasal repair of the primary cleft lip. Part II is nasal reconstruction as a secondary operation with or without lip repair. For example, nasal reconstruction may be secondary to repair of deformities of the sill, rim, limen nasi, septum, or nasal bones. Part III is an aesthetic nasal operation such as rhinoplasty, mentoplasty, or zygomaplasty.  相似文献   
47.
In order to investigate whether a hypothalamic disorder cause hypogonadism in male prolactinomas, LH pulsatile secretion was studied in 13 male patients. Serum PRL levels ranged from 186 to 45,000 ng ml-1 before treatment, and all the tumors were macroadenomas. Reduced LH secretion was revealed in 5 of 13 patients, and FSH was reduced in 1 of 13. Serum testosterone (T) levels were lower than the normal limit in all the patients. HCG tests in 3 patients showed good responses, but the peak values of T were lower than those of normal men. LH pulsatilities were examined in 5 hyperprolactinemic patients before treatment, in 4 hyperprolactinemic patients after operation, and in 8 normoprolactinemic patients after operation and/or bromocriptine treatment. There was no significant difference of the mean LH values, the frequencies of LH pulses, and amplitudes among the hyperprolactinemic patients before operation (n = 5), the normoprolactinemic patients after operation (n = 8), and normal men (n = 7). From these results, it was evident that the hypothalamus and pituitary function of male prolactinomas were well preserved, in spite of higher serum PRL levels and larger tumor size than those reported in females. It is suggested that the main cause of hypogonadism in these patients is due to testicular dysfunction resulting from excessive serum PRL.  相似文献   
48.
A 48-year-old man had histologically demonstrated cardiac involvement associated with progressive muscular dystrophy. On coronary arteriography, numerous vascular communications between the coronary arteries and the left ventricular chamber were found. These vascular communications are considered to be the arterioluminal vessels. This is the first report of a case of progressive muscular dystrophy with numerous arterioluminal vessels.  相似文献   
49.
The objective of this study is to develop a sensitive temperature-responsive material that would function near body temperature. To achieve this purpose, we compounded 2-branched and 4-branched poly(epsilon-caprolactone) macromonomers to modulate the transition temperatures of the resulting cross-linked materials. The temperature-responsive properties were studied using differential scanning calorimetry and X-ray diffraction measurements. As a result, the mixing ratios of each macromonomer or the total macromonomer concentrations were very dominant in modulating the transition temperatures. The materials could successfully control the permeation of the model drug, prednisolone, near body temperature.  相似文献   
50.
Aim:  This study aims to establish a pressure ulcers model that visualizes the microcirculation, and to examine the participation of ischemia‐reperfusion injury in the pathophysiology of pressure ulcers.
Methods:  An original system composed of a new skinfold chamber and compression device allowed loading quantitative vertical stress to the skin. An intravital microscopic technique enabled direct visualization of the microcirculation in the physiological condition and in response to pressure application. To estimate the effect of ischemia‐reperfusion injury, animals were divided into two groups: the compression‐release group in which the animals received four cycles of compression‐release which consisted of 2 hours of compression followed by 1 hour of pressure release; and the compression alone group in which the animals underwent continuous compression for 8 hours. Functional capillary density was quantified before the compression procedure and on day1 (35 hours) after the first evaluation.
Results and Conclusions:  The cyclic compression‐release procedure significantly decreased functional capillary density as compared to continuous compression, indicating that in our experimental setting repetition of ischemia‐reperfusion cycle more severely damaged the microcirculation than single prolonged ischemic insult. The finding supports the significant contribution of ischemia‐reperfusion injury to the pathophysiology of pressure ulcers at the level of dynamic in vivo microcirculation.  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