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   3096篇
  免费   38篇
  国内免费   4篇
电工技术   15篇
综合类   4篇
化学工业   129篇
金属工艺   16篇
机械仪表   11篇
建筑科学   33篇
能源动力   19篇
轻工业   54篇
石油天然气   2篇
无线电   161篇
一般工业技术   182篇
冶金工业   2353篇
原子能技术   2篇
自动化技术   157篇
  2023年   5篇
  2022年   11篇
  2021年   6篇
  2020年   10篇
  2019年   13篇
  2018年   17篇
  2017年   12篇
  2016年   9篇
  2015年   7篇
  2014年   19篇
  2013年   45篇
  2012年   24篇
  2011年   32篇
  2010年   19篇
  2009年   46篇
  2008年   45篇
  2007年   46篇
  2006年   38篇
  2005年   35篇
  2004年   41篇
  2003年   41篇
  2002年   36篇
  2001年   31篇
  2000年   31篇
  1999年   89篇
  1998年   751篇
  1997年   457篇
  1996年   297篇
  1995年   128篇
  1994年   128篇
  1993年   165篇
  1992年   29篇
  1991年   32篇
  1990年   31篇
  1989年   32篇
  1988年   33篇
  1987年   27篇
  1986年   30篇
  1985年   34篇
  1984年   3篇
  1983年   8篇
  1982年   20篇
  1981年   18篇
  1980年   24篇
  1979年   6篇
  1978年   11篇
  1977年   43篇
  1976年   112篇
  1975年   5篇
  1955年   3篇
排序方式: 共有3138条查询结果,搜索用时 0 毫秒
991.
992.
993.
Three of the four Starling forces were measured in the intact dog forelimb after anesthetization and all four of the Starling forces were measured in the same forelimb which was surgically isolated yet innervated. In the isolated forelimb, isogravimetric capillary pressure (Pci) averaged 15.6 mmHg; colloid osmotic pressure of the plasma proteins (IIp) averaged 19.9 mmHg; mean interstitial fluid pressure (Pif) was +0.4 mmHg, and the average value of interstitial colloid osmotic pressure (IIif) was 4.9 mmHg. Thus the net imbalance in the Starling forces, i.e., (Pci - Pif) - (IIp - IIif), averaged 0.3 mmHg. Furthermore, the value of IIif was consistently decreased after isolation (average decrease of 1.2 mmHg) while Pif was always increased following isolation (average increase of 4.3 mmHg). In addition, it was found that if the forelimb was denervated during isolation, then Pif was increased by an average of 2 mmHg above Pif in the innervated, isolated forelimb. In summary, these studies show that the differences between the intact and isolated forelimb are that Pci averages 10-11 mmHg in the intact forelimb and 15-16 mmHg in the isolated innervated forelimb while interstitial fluid pressure is negative in the intact limb and positive in the isolated limb.  相似文献   
994.
The transient hypocholesterolemia phenomenon observed in rats, injected i.v. with amphotericin B (1.5 mg/kg/day) for three weeks, was investigated by in vitro [14C] acetate incorporation into the liver cholesterol. The incorporation of acetate in liver slices of treated animals increased more than two-fold (p less than 0.02) when compared with controls.When amphotericin B was added in vitro to liver slices of control rats, the incorporation of acetate into cholesterol decreased to about 65% of that observed with the corresponding controls (p less than 0.01). The results are consistent with the hypothesis that initially amphotericin B causes inhibition of de novo cholesterol synthesis resulting in hypocholesterolemia which disappears on continued treatment possibly due to compensatory increased rate of cholesterol biosynthesis.  相似文献   
995.
227 patients with psoriasis and various forms of arthritis have been kept under review. Psoriasis and inflammatory arthropathy was present in 168 patients, of whom 94 have been followed up for more than 10 years. An arthritis indistinguishable from rheumatoid disease was present in 78%, distal joint arthritis in 16-6%, and deforming arthritis in 4-8%. There was a female predominance in the sex ratio of patients, although males predominated in the distal joint group (male:female 1-5:1). The peak age of onset was between 36 and 45 years, although in the deforming group the arthritis began before the age of 20 three times as commonly as it did in the indistinguishable group. Onset was acute in nearly half of the patients. At onset the distal joints were affected in one-third of the distal joint group. A synchronous onset of skin and joint changes was uncommon. Skin lesions usually preceded the arthritis but occurred after onset in 16%. Apart from in the deforming group, the arthritis was mild, judged by the number of admissions to hospital for treatment of the joint disease, and the time off work. Deterioration clinically and radiographically occurred in only a small portion of the distal joint and indistinguishable groups. Antimalarial drugs have been used in 7 patients, with deterioration of the skin condition in 4. Uveitis occurred particularly in the men of all three groups, but was most frequent in those with deforming arthritis. A family history of psoriasis was obtained in 26% of first-degree relatives and 13% of second-degree relatives. A history of polyarthritis was most common in patients in the deforming group. The sheep cell agglutination test was negative in the majority, but was positive in 16% of the indistinguishable group, fluctuating in a further 10%. A small number of joints only deteriorated radiographically (10% of the distal and indistinguishable groups). The men in the distal group showed greater radiographic changes and more deterioration in the terminal interphalangeal joints of the fingers than the women. Similarly they showed more deterioration of the metatarsophalangeal joints than the women. 18 patients died, one with gastric haemorrhage resulting from treatment of exfoliative psoriasis with immunosuppressive therapy, and 2 from bronchopneumonia thought to be related to immobility caused by the arthritis.  相似文献   
996.
997.
Experience of fluoroscopically controlled transbronchial biopsy using the fibreoptic bronchoscope in 30 patients with solitary lesions in the peripheral lung fields beyond bronchoscopic vision is described. At the time of submitting this paper for publication (30 January 1978) no account of the technique has been reported in the British literature. In 21 patients with a final diagnosis of bronchial carcinoma a positive biopsy diagnosis was obtained in 14 (67%). Five of seven patients (71%) with a final diagnosis of an inflammatory condition showed evidence of acute or chronic inflammation on biopsy. There were no complications. The procedure is indicated when a definitive diagnosis is required for management planning in clinically inoperable patients, or when a tissue diagnosis is particularly desired in an attempt to obviate the need for thoracotomy. The relative safety makes this the biopsy technique of choice for the evaluation of isolated peripheral pulmonary opacities.  相似文献   
998.
Mouse peritoneal macrophages in culture exposed to mouldy hay dust, Micropolyspora faeni or glycopeptide or protein/glycoprotein fractions from this organism show marked biochemical changes. For comparison the interaction of cultured macrophages with zymosan has been investigated. All these agents induce the release of hydrolytic enzymes from macrophages, even in the absence of serum in the medium. The release is time- and dose-dependent and is not associated with loss of the cytoplasmic enzyme lactate dehydrogenase or any other sign of cell death. The parallelism between the capacity of these agents to activate the complement system via the alternative pathway and to induce inflammatory responses in vivo and selective lysosomal enzyme secretion from cultures of macrophages is discussed. The in vitro phenomena seen with mouldy hay dust, M. faeni, the protein/glycoprotein and the glycopeptide derived from it, may be relevant to understanding the role of mononuclear phagocytes in the disease farmer's lung and other inflammatory reactions.  相似文献   
999.
Stannous or stannic chlorides reduced the growth rate of K. aerogenes, Ps. reptilovora and an unidentified bacterium in a minimal liquid medium and on agar plates. The greatest effect was observed with K. aerogenes and was accompanied by a decreased viability, but 100% survival occurred with other strains. The metal was loosely bound to the cells and there was no direct correlation between the amount adsorbed and the biological response.  相似文献   
1000.
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