全文获取类型
收费全文 | 11928篇 |
免费 | 316篇 |
国内免费 | 1篇 |
出版年
2020年 | 81篇 |
2019年 | 81篇 |
2018年 | 259篇 |
2017年 | 206篇 |
2016年 | 300篇 |
2015年 | 289篇 |
2014年 | 362篇 |
2013年 | 493篇 |
2012年 | 475篇 |
2011年 | 494篇 |
2010年 | 320篇 |
2009年 | 222篇 |
2008年 | 330篇 |
2007年 | 373篇 |
2006年 | 362篇 |
2005年 | 342篇 |
2004年 | 292篇 |
2003年 | 323篇 |
2002年 | 285篇 |
2001年 | 268篇 |
2000年 | 219篇 |
1999年 | 174篇 |
1998年 | 83篇 |
1992年 | 227篇 |
1991年 | 219篇 |
1990年 | 175篇 |
1989年 | 207篇 |
1988年 | 227篇 |
1987年 | 236篇 |
1986年 | 206篇 |
1985年 | 236篇 |
1984年 | 190篇 |
1983年 | 158篇 |
1982年 | 80篇 |
1980年 | 78篇 |
1979年 | 229篇 |
1978年 | 151篇 |
1977年 | 130篇 |
1976年 | 134篇 |
1975年 | 161篇 |
1974年 | 263篇 |
1973年 | 257篇 |
1972年 | 243篇 |
1971年 | 242篇 |
1970年 | 252篇 |
1969年 | 243篇 |
1968年 | 185篇 |
1967年 | 185篇 |
1966年 | 167篇 |
1965年 | 124篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
151.
The levels of serum fatty acids in the serum and in the serum fractions of cholesterol esters (ECH) and triglycerides (TG) and the levels of these acids in these fractions of platelets were compared in healthy controls and in patients with clinically manifested coronary arterial disease. Decreased level of linoleic acid was found in the serum and in the ECH fraction of the serum in the patients, with a rise in the level of palmitic acid in the ECH fraction of the serum of these patients. The level of linoleic acid in the ECH and TG platelet fractions in these patients was not different from that in the healthy controls, while in the platelet TG fraction of the patients the level of palmitoleic acid was raised, and the level of oleic acid was increased in the platelet ECH fraction. 相似文献
152.
S Koz?owski J Chwalbińska-Moneta M Vigas H Kaciuba-U?ci?ko K Nazar 《European journal of applied physiology and occupational physiology》1983,52(1):131-135
The aim of this study was to provide information concerning the mechanism of exercise-induced stimulation of growth hormone (GH) release in human subjects. For this reason serum GH as well as some hemodynamic variables and blood concentrations of noradrenaline (NA), insulin (IRI), lactate (LA), glucose (BG), and free fatty acids (FFA) were determined in seven healthy male subjects exercising on a bicycle ergometer with arms or legs and running on a treadmill at equivalent oxygen consumption levels. Significantly greater increases in serum GH concentration accompanied arm exercises than those observed during the leg exercises. This was accompanied by greater increases in heart rate, blood pressure, and plasma NA and blood lactate concentrations. Serum IRI decreased during both leg exercises and did not change during the arm exercise. There were no differences in BG and plasma FFA concentrations between the three types of exercise. The role of humoral and neural signals responsible for the greater GH response to arm exercise is discussed. The findings are consistent with the hypothesis that neural afferent signals sent by muscle "metabolic receptors" participate in the activation of GH release during physical exercise. It seems likely that the stimulation of these chemoreceptors is more pronounced when smaller muscle groups are engaged at a given work load. However, a contribution of efferent impulses derived from the brain motor centres to the control system of GH secretion during exercise is also possible. 相似文献
153.
154.
155.
156.
157.
158.
159.
Jan Zarzycki Alina Peryt Barbara Klubińska Teresa Hajac Krystyna Żak 《Histochemistry and cell biology》1969,18(4):314-320
Zusammenfassung Es wurden mit histochemischen Methoden Milchdrüsen von Meerschweinchen in physiologischer und durch Kastration während der Laktationsperiode hervorgerufener Involution untersucht. Nachgewiesen wurden alkalische und saure Phosphatase (APh und SPh), unspezifische Esterase, Sukzinodehydrase, SH-Gruppen, Nukleinsäuren und Lipide. — Die Aktivität der SPh nimmt während der Involution zu. Die Bedeutung dieses Enzyms für den Rückbildungsprozeß des Drüsengewebes wird diskutiert. — Das Vorkommen der APh-Aktivität in Drüsenendstücken im Involutionsstadium kann auf die Beteiligung dieses Enzyms an der Rückresorption der mit der Milch ausgeschiedenen Substanzen hinweisen. — Zwischen der Aktivität der unspezifischen Esterase und dem Gehalt sowie der Lokalisation von Lipiden besteht eine Abhängigkeit. — Es konnten keine Unterschiede in der Sukzinodehydraseaktivität und dem DNS-Gehalt aufgezeigt werden. — Die Verminderung von SH-Gruppen und RNS hängt mit dem Aufhören der Sekretionsproduktion durch die Zellen der Drüsenendstücke der Milchdrüsen zusammen.
Histochemical studies on the involution mechanism of the mammary gland
Summary Histochemical methods were used to study mammary glands of guinea pigs in the course of physiologic involution and that induced by castration during lactation. Alkaline and acid phosphatases, unspecific esterase, succinic dehydrogenase, SH groups, nucleic acids and lipids were determined. Acid phosphatase activity was found to be increased in mammary glands, subject to involution. The participation of the enzyme in the involutionary process of the gland tissue is discussed. The distribution of alkaline phosphatase in the secretory sections of the gland during involution would suggest the participation of the enzyme in the reabsorption of the substance secreted with milk. A correlation existing between the activity of unspecific esterase, the level and distribution of lipids in the mammary gland could be established. No differences were detected in the activity of succinic dehydrogenase and DNA level. A decrease in SH groups and RNA content is related to cessation of milk secretion.相似文献
160.