全文获取类型
收费全文 | 1339311篇 |
免费 | 136749篇 |
国内免费 | 845篇 |
专业分类
1476905篇 |
出版年
2018年 | 11402篇 |
2016年 | 16224篇 |
2015年 | 22793篇 |
2014年 | 26570篇 |
2013年 | 37621篇 |
2012年 | 42395篇 |
2011年 | 42702篇 |
2010年 | 29175篇 |
2009年 | 26923篇 |
2008年 | 38245篇 |
2007年 | 39423篇 |
2006年 | 36958篇 |
2005年 | 35684篇 |
2004年 | 35437篇 |
2003年 | 34178篇 |
2002年 | 33282篇 |
2001年 | 56744篇 |
2000年 | 57071篇 |
1999年 | 45947篇 |
1998年 | 17427篇 |
1997年 | 18177篇 |
1996年 | 17156篇 |
1995年 | 16146篇 |
1994年 | 15781篇 |
1993年 | 15655篇 |
1992年 | 38397篇 |
1991年 | 37394篇 |
1990年 | 36711篇 |
1989年 | 35847篇 |
1988年 | 33242篇 |
1987年 | 31816篇 |
1986年 | 29517篇 |
1985年 | 29643篇 |
1984年 | 24769篇 |
1983年 | 21337篇 |
1982年 | 16764篇 |
1981年 | 15053篇 |
1980年 | 14192篇 |
1979年 | 23541篇 |
1978年 | 18662篇 |
1977年 | 16908篇 |
1976年 | 15822篇 |
1975年 | 17347篇 |
1974年 | 18655篇 |
1973年 | 18438篇 |
1972年 | 16570篇 |
1971年 | 15298篇 |
1970年 | 13133篇 |
1969年 | 12589篇 |
1968年 | 11377篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
E. Longo J. Cansado C. Sieiro P. Calo J. B. Velázquez T. G. Villa 《World journal of microbiology & biotechnology》1992,8(2):147-150
Fermentative behaviour and cell growth have been studied in grape juice inoculated either with two killerSaccharomyces cerevisiae wild strains or with their Acridine Orange-cured isogenic counterparts. The number of viable cells/ml at the beginning of the fermentation, as well as during exponential growth, were higher in grape juices inoculated with the cured strains. The CO2 production, fermentative rate and ethanol and acetic acid production were also higher in the cured strains, particularly during the stage of active fermentation. These differences, however, were minimal at the end of the fermentations. 相似文献
962.
J W Funder 《The Journal of steroid biochemistry and molecular biology》1992,43(5):389-394
Glucocorticoid hormones are secreted uniquely from the zona fasciculata of the adrenal cortex, with marked circadian variation in basal levels and acute elevation in response to stress. Glucocorticoid receptors are almost ubiquitously distributed, and mediate a wide range of tissue-specific responses; in addition to classical, [3H]dexamethasone-binding GR (Type II receptors) there is excellent evidence that Type I sites (MR) act as mineralocorticoid receptors in some tissues but high affinity glucocorticoid receptors in others. Particular issues to be addressed in the presentation include: (i) the extent to which glucocorticoid receptor occupancy is modulated by extracellular (plasma-binding enzymes) or intracellular (proto-oncogenes) factors; (ii) whether or not there are specific response elements for Type I and II receptors; (iii) putative physiological roles for Type I, high affinity glucocorticoid receptors; (iv) evidence for glucocorticoid receptors other than classical GR and "MR". In summary, glucocorticoid receptors appear to be a final common pathway mediating and/or modulating circadian rhythms and stress responses. Cell-and tissue-specificity of response to a whole-body signal is determined by local pre-receptor, receptor and genomic differences. On the basis of previous studies on glucocorticoid secretion, and recent information on glucocorticoid action, it would at last appear possible to begin to construct a coherent physiology for glucocorticoid hormones. 相似文献
963.
A. J. Swerdlow A. J. Douglas G. V. Hudson B. V. Hudson M. H. Bennett K. A. MacLennan 《BMJ (Clinical research ed.)》1992,304(6835):1137-1143
OBJECTIVE--To analyse the risk of second primary cancers during long term follow up of patients with Hodgkin''s disease. DESIGN--Cohort study. SETTING--The British National Lymphoma Investigation (a collaborative group of over 60 participating centres in Britain treating lymphomas). PATIENTS--2846 patients first treated for Hodgkin''s disease during 1970-87, for whom follow up was complete in 99.8%. MAIN OUTCOME MEASURES--Second primary cancers; uniform pathology reviews confirmed the diagnosis of Hodgkin''s disease and of second primary non-Hodgkin''s lymphomas. RESULTS--113 second primary cancers occurred. Relative risk of cancer other than Hodgkin''s disease was 2.7 (95% confidence interval 2.3 to 3.3) compared with the general population, with significant risk of leukaemia (16.0(9.1 to 26.0)); non-Hodgkin''s lymphoma (16.8(9.8 to 26.9)); and cancers of the colon (3.2 (1.4 to 6.2)), lung (3.8 (2.6 to 5.4)), bone (15.1 (1.8 to 54.7)), and thyroid (9.4 (1.1 to 33.9)). Absolute excess risk associated with treatment was greater for solid tumours than for leukaemia and lymphomas. Relative risk of leukaemia increased soon after treatment, reaching a peak after five to nine years. It was increased substantially after chemotherapy (27.9 (12.7 to 52.9)), combined treatment with radiotherapy and chemotherapy (21.5 (7.9 to 46.8)), and relative to number of courses of chemotherapy but was not significantly increased after radiotherapy (2.5 (0.1 to 14.1)). Relative risk of non-Hodgkin''s lymphoma increased in the first five years after treatment and remained high but showed no clear relation with type or extent of treatment. Relative risk of solid tumours was less raised initially but increased throughout follow up and for lung cancer 10 years or more after entry was 8.3 (4.0 to 15.3). The risk of solid tumours increased after treatments including radiotherapy and after chemotherapy alone. The risk after chemotherapy increased significantly with time since first treatment. CONCLUSION--The risk of solid cancer, not of leukaemia, is the major long term hazard of treatment for Hodgkin''s disease, and this seemed to apply after chemotherapy as well as after radiotherapy. These risks of second cancers are important in choice of treatment and in follow up of patients, but they are small compared with the great improvements in survival which have been brought about by modern therapeutic methods for Hodgkin''s disease. 相似文献
964.
965.
J O Macaulay G L Warne Z S Krozowski 《The Journal of steroid biochemistry and molecular biology》1992,42(3-4):259-265
Human placenta contains the methyltrienolone binding protein (MTBP), an androgen binding protein which is distinct from the androgen receptor. This study demonstrates that the human choriocarcinoma cell line (JEG-3) also contains the MTBP and that in both human placenta and JEG-3 cells the MTBP is located exclusively in the nucleus and in particular is associated with DNase 1 resistant chromatin. 相似文献
966.
J L Maggs P Morgan B K Park 《The Journal of steroid biochemistry and molecular biology》1992,42(1):65-76
The oxygenated-metabolite profiles of exogenous 17 beta-oestradiol (E2) in adult male and female Wistar rats have been characterized and major sex-dependent biotransformations observed which correlate with the regioselectivities of known sexually differentiated hepatic P450. [6,7-3H]E2 (27 micrograms/kg) was given i.v. The metabolites of E2 were rapidly and extensively excreted in bile (46 and 78% of the dose over 1 and 6 h, respectively). Female rats metabolized E2 by one major pathway: oxidation to oestrone (E1) followed by C-2 hydroxylation and O-methylation; the principal aglycones (0-1 h bile collections) were E1 (14%), 2-hydroxyE1 (2-OHE1) (42%) and 2-methoxyE1 (24%). Male rats metabolized E2 principally by two parallel composite pathways of E1 hydroxylation which yielded a complex mixture of mono- and di-oxygenated compounds: 15 alpha-OHE1 (33%), 2,15 alpha-diOHE1 (7%), and 2-methoxy-15 alpha OHE1 (14%); 16 alpha-OHE1 (13%), 2,16 alpha-diOHE1 (4%) and 2-methoxy-16 alpha-OHE1 (2%). 15 alpha-Hydroxylation was unique to males. The balance of aromatic and alkyl hydroxylation in males was dose-dependent: at 3 mg/kg, 15 alpha-hydroxylation was decreased approx. 50% in favour of 2-hydroxylation whilst 16 alpha-hydroxylation was largely unaffected. The male-specific 15 alpha-hydroxylation and male-predominant 16 alpha-hydroxylation of E1 derived from E2 in vivo may be ascribable to the male-specific isoforms P450IIC13 and P450IIC11, respectively. 相似文献
967.
968.
M. Fisher 《BMJ (Clinical research ed.)》1992,305(6862):1107-1108
969.
970.
J. Neuberger 《BMJ (Clinical research ed.)》1992,305(6867):1486-1488
The Tomlinson report, with its emphasis on primary and community care, offers great scope to community health services, for long the poor relation of the NHS, and particularly poorly resourced in London. The aim is to create services that break down the barriers between primary, secondary, and tertiary health care and concentrate on providing high quality care tailored to individual patients'' needs. Thus a range of flexible options needs to be developed between acute hospital based care and the standard home care arrangements currently provided by district nurses. Examples, include hospital at home schemes, nursing beds, and rehabilitation beds. Together community and primary care services need to consider weekend coverage, to conduct research, and to become a setting for education. The infrastructure for primary and community care must, however, be put in place before acute facilities are shut. 相似文献