全文获取类型
收费全文 | 1412946篇 |
免费 | 104996篇 |
国内免费 | 2373篇 |
专业分类
耳鼻咽喉 | 20231篇 |
儿科学 | 48584篇 |
妇产科学 | 37815篇 |
基础医学 | 200279篇 |
口腔科学 | 40208篇 |
临床医学 | 121307篇 |
内科学 | 287124篇 |
皮肤病学 | 31308篇 |
神经病学 | 111598篇 |
特种医学 | 55250篇 |
外国民族医学 | 682篇 |
外科学 | 212577篇 |
综合类 | 28187篇 |
现状与发展 | 2篇 |
一般理论 | 423篇 |
预防医学 | 110342篇 |
眼科学 | 30537篇 |
药学 | 102909篇 |
2篇 | |
中国医学 | 3005篇 |
肿瘤学 | 77945篇 |
出版年
2021年 | 11062篇 |
2019年 | 11930篇 |
2018年 | 17114篇 |
2017年 | 12916篇 |
2016年 | 13656篇 |
2015年 | 15635篇 |
2014年 | 21679篇 |
2013年 | 31877篇 |
2012年 | 44779篇 |
2011年 | 47338篇 |
2010年 | 27548篇 |
2009年 | 25963篇 |
2008年 | 43627篇 |
2007年 | 46812篇 |
2006年 | 46386篇 |
2005年 | 45676篇 |
2004年 | 44432篇 |
2003年 | 42606篇 |
2002年 | 40211篇 |
2001年 | 67216篇 |
2000年 | 69573篇 |
1999年 | 59176篇 |
1998年 | 16291篇 |
1997年 | 14692篇 |
1996年 | 15109篇 |
1995年 | 14224篇 |
1994年 | 13535篇 |
1993年 | 12513篇 |
1992年 | 46204篇 |
1991年 | 45105篇 |
1990年 | 43712篇 |
1989年 | 41596篇 |
1988年 | 38299篇 |
1987年 | 37513篇 |
1986年 | 34893篇 |
1985年 | 33509篇 |
1984年 | 25004篇 |
1983年 | 20969篇 |
1982年 | 12142篇 |
1981年 | 11087篇 |
1979年 | 22027篇 |
1978年 | 15267篇 |
1977年 | 12874篇 |
1976年 | 11992篇 |
1975年 | 13028篇 |
1974年 | 15075篇 |
1973年 | 14515篇 |
1972年 | 13286篇 |
1971年 | 12044篇 |
1970年 | 11402篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
It has been claimed that carcinoma of the large intestine is extremely rare in the indigenous black population in Africa. Furthermore, the incidence of colorectal carcinoma in black Africans is said to increase when they abandon their customary diet and adopt a more westernised diet. Although colorectal carcinoma is not a common condition in our region, our experience at Mpilo Hospital over the last eight years suggest that it is by no means a rare condition. During this period we treated 90 black patients giving an average admission rate of 11.25 new cases a year. Virtually all our patients would have been on their customary high roughage diet because they either came from rural areas (55.7 percent) or if they lived in town (44.3 percent) they belonged to the working class. 相似文献
992.
Fatigue during stretch-shortening cycle exercises: changes in mechanical performance of human skeletal muscle 总被引:6,自引:0,他引:6
Stretch-shortening cycle (SSC), which is a normal contraction behavior of muscle, was used as a model to investigate muscular fatigue. Nine male volunteers were subjected to 100 repeated and exhaustive SSC contractions of the forearm extensors using a special sledge apparatus incorporating a force plate system. The fatigue contractions were performed on submaximal levels but the before-after comparison also included maximal drop-jump condition on the sledge as well as falls on to the floor. The results indicated that in the 100 submaximal SSCs the fatigue was characterized by increases in the contact times for both the eccentric and concentric phases of SSC, but the influence was more pronounced on the concentric part. The force-time curves during contact on the platform were influenced by fatigue so that the initial force peak became higher and the subsequent initial drop of force more pronounced. During submaximal and maximal drops, the angular velocities changed in the two phases of SSC. With progressing fatigue, the eccentric maximal angular velocity increased and the corresponding concentric velocities decreased. These changes were accompanied by slight changes in the elbow joint mechanism with respect to the contact, release, and maximal flexion angles. The results suggest that repeated SSC induces fatigue and the fatigue effects on the mechanical behavior of the muscle are very much similar to those induced by either isometric or concentric fatigue contractions. However, the transfer of the energy between eccentric and concentric phases was drastically reduced and this implies that SSCs can be used effectively to examine the fatiguability of the system regulating muscle stiffness during exercise. 相似文献
993.
In the cat synapses between vesicle containing profiles were observed in ventral and dorsolateral pontine nuclei. The presynaptic elements consisted of two types of axon terminals: axon terminals characterized by a population of small (38-40 nm) round synaptic vesicles (SSV) and axon terminals containing pleomorphic synaptic vesicles (PSV). The postsynaptic pale elements (PP) had pleomorphic vesicles and some features attributed to dendrites. In the dorsolateral pontine nucleus most of PP profiles took part in serial synapses, usually as an intermediate component, they were rarely observed in triads. On the basis of their electron microscopical appearance and synaptic relations they might be considered to represent a dendritic part of putative interneurons. 相似文献
994.
Skin Granulomas due to Mycobacterium gordonae 总被引:2,自引:0,他引:2
P. Gengoux M.D. F. Portaels M.D. J. M. Lachapeile M.D. D. E. Minnikin M.D. D. Tennstedt M.D. P. Tamigneau M.D. 《International journal of dermatology》1987,26(3):181-184
A 38-year-old woman presented with small, ulcerated, red or bluish nodules on the right hand, clinically resembling mycobacterial granulomas; these appeared a few months after a bite by a rat, while the patient was collecting frogs in a pond in the Belgian Ardennes. The histopathologic picture was compatible with a diagnosis of mycobacterial infection and rare acid-fast bacilli could be found. Repeated bacteriologic investigations were performed and these led to the identification of a strain displaying characteristics of Mycobacterium gordonae. The skin condition responded well to rifampicin (300 mg/day) within 6 months. 相似文献
995.
K Nieber P Henklein T Ott P Oehme 《Zeitschrift für die gesamte innere Medizin und ihre Grenzgebiete》1987,42(18):501-506
This issue comprises selected topics of CCK peptides. CCK peptides are linear peptides and were found within and outside the CNS. There is growing evidence that CCK peptides play a physiological role in food intake, contraction of gallbladder and regulation of motility of the gastrointestinal system. New aspects of the CCK research are concentrated on interaction with other transmitter systems especially with the dopamine and opioid system. The therapeutic action to improve clinical symptoms in human is unclear up to new. World-wide, the interest is focused to determine the potential of CCK peptides as an antipsychotic agent by controlled clinical studies. 相似文献
996.
In the upper limb, diffuse cavernous haemangiomas occur infrequently but their treatment is often unsatisfactory and the result of surgical excision disappointing. Four cases of these diffuse haemangiomas are described and their management discussed. 相似文献
997.
Sutureless bowel anastomosis using Nd:YAG laser 总被引:5,自引:0,他引:5
Small bowel anastomoses were performed without sutures by using the Nd:YAG laser to produce welded enterotomies. Optimal energy levels for contact and noncontact laser were determined. Anastomoses produced using five target energy levels between 100 and 500 J were examined. Short-term anastomotic strength of these enterotomies was measured 1 min after the welding. Bursting pressure of the laser welded enterotomies was compared to the bursting pressure of traditional two-layer, inverting, interrupted sutured bowel anastomoses. The overall mean bursting pressure of non-contact-welded enterotomies was 50.6 mmHg. Optimal laser settings determined in this initial phase were then used to produce anastomoses in rabbits which are recovered postoperatively for 1 or 2 weeks in order to examine long-term viability and integrity of the anastomoses. All chronic rabbit preparations recovered without complication. The mean bursting pressure was 200 mmHg, not significantly different from that of uncut bowel or two-layer sutured anastomosis. 相似文献
998.
999.
H R Schumacher A L Osterman S J Choi P B Weisz 《Clinical orthopaedics and related research》1987,(219):221-225
Painful calcinosis appeared at the wrist of an eight-year-old girl with lead poisoning. Careful history revealed that calcification occurred at the site of previous extravasation of calcium disodium edetate (EDTA) used in chelation therapy. Light microscopic, ultrastructural, electron activation, and X-ray diffraction studies demonstrated apatites with some suggestion of an admixture of octacalcium phosphate. 相似文献
1000.
To determine whether therapy with exogenous insulin or sulfonylureas results in a postprandial pattern of carbohydrate metabolism in patients with non-insulin-dependent diabetes mellitus (NIDDM) that resembles that in nondiabetic individuals, we employed a dual-isotope technique combined with forearm catheterization to examine meal disposition in NIDDM patients, before and after 3 mo of therapy with tolazamide and after 3 mo of therapy with exogenous insulin, with a randomized crossover design. Results were compared with those observed in nondiabetic subjects. Although both forms of therapy improved chronic glycemic control (glycosylated hemoglobin concentration went from 9.6 +/- 0.7 to 7.6 +/- 0.5 and 7.1 +/- 0.2%, respectively, P less than .01), exogenous insulin resulted in a lower postprandial glycemic response than tolazamide (P less than .001). Both agents comparably increased (P less than .01) fasting and integrated postprandial insulin concentrations. However, the initial rate of postprandial increase was greater with exogenous insulin (P less than .05). Tolazamide (P less than .05) but not exogenous insulin increased postprandial C-peptide concentrations. However, tolazamide did not improve the deficient early insulin release. Both agents (P less than .05) lowered postabsorptive hepatic glucose release (from 2.8 +/- 0.3 to 2.3 +/- 0.2 mg . kg-1 . min-1), but not to normal rates (1.8 +/- 0.1 mg . kg-1 . min-1).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献