全文获取类型
收费全文 | 6217篇 |
免费 | 503篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 67篇 |
儿科学 | 281篇 |
妇产科学 | 168篇 |
基础医学 | 873篇 |
口腔科学 | 135篇 |
临床医学 | 650篇 |
内科学 | 1283篇 |
皮肤病学 | 121篇 |
神经病学 | 777篇 |
特种医学 | 571篇 |
外国民族医学 | 1篇 |
外科学 | 796篇 |
综合类 | 146篇 |
预防医学 | 355篇 |
眼科学 | 55篇 |
药学 | 208篇 |
中国医学 | 14篇 |
肿瘤学 | 233篇 |
出版年
2021年 | 72篇 |
2019年 | 54篇 |
2018年 | 80篇 |
2017年 | 57篇 |
2016年 | 66篇 |
2015年 | 108篇 |
2014年 | 160篇 |
2013年 | 214篇 |
2012年 | 252篇 |
2011年 | 251篇 |
2010年 | 154篇 |
2009年 | 156篇 |
2008年 | 264篇 |
2007年 | 281篇 |
2006年 | 226篇 |
2005年 | 237篇 |
2004年 | 224篇 |
2003年 | 237篇 |
2002年 | 218篇 |
2001年 | 184篇 |
2000年 | 198篇 |
1999年 | 152篇 |
1998年 | 180篇 |
1997年 | 125篇 |
1996年 | 120篇 |
1995年 | 84篇 |
1994年 | 91篇 |
1993年 | 80篇 |
1992年 | 111篇 |
1991年 | 107篇 |
1990年 | 106篇 |
1989年 | 114篇 |
1988年 | 137篇 |
1987年 | 129篇 |
1986年 | 115篇 |
1985年 | 90篇 |
1984年 | 93篇 |
1983年 | 84篇 |
1982年 | 61篇 |
1981年 | 63篇 |
1980年 | 53篇 |
1979年 | 67篇 |
1978年 | 73篇 |
1977年 | 68篇 |
1976年 | 56篇 |
1975年 | 42篇 |
1974年 | 42篇 |
1973年 | 49篇 |
1972年 | 50篇 |
1969年 | 43篇 |
排序方式: 共有6734条查询结果,搜索用时 31 毫秒
81.
82.
Shumikhina S Guay J Duret F Molotchnikoff S 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2004,158(2):223-232
Synchronization of neuronal activity has been proposed as a binding mechanism for integration of image properties into one coherent percept. In the present study, we investigated the contextual modulation of synchronization to random dot patterns. Coherent motion of random dots evoked well synchronized responses in area 17 of anaesthetized cats when the stimulus was presented in the compound receptive field of recorded sites. Gradually changing the directional coherence of random dots in the surround while maintaining fully coherent motion of the stimulus in the receptive field significantly suppressed synchronization of neuronal activity for some stimulus conditions. However, usually one or two peaks of increased synchronization were found in the surround coherence tuning curves with low (8–12%) and/or moderate (25–50%) coherence in the surround. At the population level, synchronization was significantly depressed with incoherent motion in the receptive field and when both the surround and the receptive field were jointly stimulated with 0% coherence. The intriguing finding was the discovery of two distinct groups of cells with opposite synchronization changes dependent on the presence or absence of significant synchronization in their spontaneous activity. The latter group of neurons showed peaks of increased synchronization with lower surround coherence, thus probably being more sensitive to the direction of the surround motion. Overall, our findings support the notion that binding of stimulus properties can be achieved by synchronized activity of cortical cells. However, our findings go further than the original hypothesis of feature binding by synchrony to show that synchronization of cortical activity may be directly related to the decision making processes, which in turn are related to the threshold of perception of coherent motion. 相似文献
83.
H. Noreen L. Steiner M. Davidson S. Johnson M. Segall A. B. Begovich 《Tissue antigens》1997,49(5):512-516
Six new DPB1 alleles were identified by PCR-SSOP methodologies in the course of a retrospective study of the role of HLA matching in the outcome of unrelated donor bone marrow transplantation. Sequencing confirmed that five of these alleles (DPB1*5901, *6801, *7101, *7201, and *7301) represent novel combinations of previously described sequence motifs in the variable regions of DPB1; the sixth (DPB1*7001) appears to result from a novel point mutation. These data support previous observations which suggest that multiple mechanisms, including segmental exchange and mutation, appear to be responsible for generating sequence diversity at the DPB1 locus. The extremely low discrepancy rate of 0.1% between the two laboratories which typed the samples, and the ability to predict the new sequences from probe hybridization patterns, indicate that SSOP is an accurate and efficient method for studying polymorphism at DPB1. 相似文献
84.
Conservative treatment of cervical pregnancy by curettage and local prostaglandin injection 总被引:2,自引:4,他引:2
Spitzer D; Steiner H; Graf A; Zajc M; Staudach A 《Human reproduction (Oxford, England)》1997,12(4):860-866
Recently, various conservative regimens for the treatment of cervical
pregnancy have been introduced to preserve fertility in young women, with
methotrexate being one of the most widely used drugs. The success of
conservative treatment depends on early preoperative diagnosis. We report
three cases of first trimester cervical pregnancy, successfully treated by
curettage to evacuate the conceptus, followed by local prostaglandin
instillation to prevent severe haemorrhage. In one patient, intra-amniotic
instillation of hyperosmolar glucose was necessary to terminate fetal
cardiac activity. beta-Human chorionic gonadotrophin returned to normal
within 3 weeks in one patient and within 7 weeks in another, both of whom
became pregnant again within 1 year, resulting in term deliveries. The
third patient was lost to follow-up after 1 week. The advantage of
prostaglandin and curettage is the absence of major side-effects to the
mother or the fetus of a subsequent pregnancy. The management strategies
used in the treatment of cervical pregnancies and the results obtained
since the introduction of methotrexate in 1989 are discussed in the context
of previously published literature. The incidence of subsequent pregnancies
among women treated medically versus women treated surgically is reported.
相似文献
85.
Mutations in Emery-Dreifuss muscular dystrophy and their effects on emerin protein expression 总被引:2,自引:1,他引:2
Manilal S; Recan D; Sewry CA; Hoeltzenbein M; Llense S; Leturcq F; Deburgrave N; Barbot J; Man N; Muntoni F; Wehnert M; Kaplan J; Morris GE 《Human molecular genetics》1998,7(5):855-864
Seventeen families with Emery-Dreifuss muscular dystrophy (EDMD) have been
studied both by DNA sequencing and by emerin protein expression. Fourteen
had mutations in the X-linked emerin gene, while three showed evidence of
autosomal inheritance. Twelve of the 14 emerin mutations caused early
termination of translation. An in-frame deletion of six amino acids from
the C-terminal transmembrane helix caused almost complete absence of emerin
from muscle with no localization to the nuclear membrane, although mRNA
levels were normal. This shows that mutant emerin proteins are unstable if
they are unable to integrate into a membrane. A 22 bp deletion in the
promoter region was expected to result in reduced emerin production, but
normal amounts of emerin of normal size were found in leucocytes and
lymphoblastoid cell lines. This shows that DNA analysis is necessary to
exclude emerin mutations in suspected X-linked EDMD. Emerin levels in
female carriers often deviated from the expected 50% and this was due, in
at least two families, to skewed emerin mRNA expression from the normal and
mutated alleles. In one family with a novel deletion of the last three
exons of the emerin gene, a carrier had a cardiomyopathy and very low
emerin levels (<5% of normal) due to skewed X-inactivation. In the three
autosomal cases of EDMD, emerin was normal on western blots of blood cells,
which suggests that autosomal EDMD is not caused by indirect reduction of
emerin levels.
相似文献
86.
Anxiety during pregnancy and fetal attachment after in-vitro fertilization conception 总被引:3,自引:4,他引:3
McMahon CA; Ungerer JA; Beaurepaire J; Tennant C; Saunders D 《Human reproduction (Oxford, England)》1997,12(1):176-182
The aim of this study was to compare 70 couples who had conceived by in-
vitro fertilization (IVF) with 63 matched controls for the prevalence of
anxiety and quality of attachment to the baby during pregnancy. Results for
mothers showed no group differences using a global measure of anxiety, the
Spielberger State-Trait Anxiety Inventory. However, pregnancy-specific
measures revealed significantly higher levels of anxiety in IVF mothers
about the survival and normality of their unborn babies, about damage to
their babies during childbirth and about separating from their babies after
birth. When IVF mothers were differentiated according to the number of
treatment cycles, more differences in anxiety level were revealed, with
most increases occurring in mothers who had experienced two or more
treatment cycles. IVF fathers did not differ from controls on the global
anxiety measure. No data on pregnancy-specific anxiety were available for
fathers. Neither IVF mothers nor IVF fathers differed from controls on
measures of attachment to the baby during pregnancy. Results are discussed
in the context of the need for researchers to employ differentiated and
issue-specific measures to identify concerns that may be unique to IVF
couples. Clinical implications regarding the need for psychological support
during pregnancy are also discussed.
相似文献
87.
88.
Eric B. Hekler Jason Rubenstein Elliot J. Coups Suzanne Gilligan Alexander W. Kusnecov Richard J. Contrada Matthew J. Steiner Alan K. Tannenbaum Elaine A. Leventhal and Tyrone J. Krause 《Journal of Applied Biobehavioral Research》2007,12(2):65-81
Inflammatory activity has been associated with both coronary disease and depressive symptoms. We sought to determine whether inflammatory markers in myocardial infarction (MI) patients are prospectively associated with depressive symptomatology. Participants were a convenience sample of MI patients. Depressive symptoms were assessed soon after the MI and again 7 months postdischarge. Inflammatory markers examined were interleukin-6 (IL-6) and interleukin-1β. Results suggest no significant cross-sectional association between inflammatory markers and depressive symptoms at baseline. However, bivariate and multiple regression analyses revealed a significant positive prospective association between baseline IL-6 and depressive symptoms 7 months later ( β = .57, p < .01). The results suggest that temporal considerations are important in understanding relationships between inflammation and depressive symptoms following MI. 相似文献
89.
Tardivel A Tinel A Lens S Steiner QG Sauberli E Wilson A Mackay F Rolink AG Beermann F Tschopp J Schneider P 《European journal of immunology》2004,34(2):509-518
The TNF family ligand B cell-activating factor (BAFF, BLyS, TALL-1) is an essential factor for B cell development. BAFF binds to three receptors, BAFF-R, transmembrane activator and CAML interactor (TACI), and B cell maturation antigen (BCMA), but only BAFF-R is required for successful survival and maturation of splenic B cells. To test whether the effect of BAFF is due to the up-regulation of anti-apoptotic factors, TACI-Ig-transgenic mice, in which BAFF function is inhibited, were crossed with transgenic mice expressing FLICE-inhibitory protein (FLIP) or Bcl-2 in the B cell compartment. FLIP expression did not rescue B cells, while enforced Bcl-2 expression restored peripheral B cells and the ability to mount T-dependent antibody responses. However, many B cells retained immaturity markers and failed to express normal amounts of CD21. Marginal zone B cells were not restored and the T-independent IgG3, but not IgM, response was impaired in the TACI-IgxBcl-2 mice. These results suggest that BAFF is required not only to inhibit apoptosis of maturating B cells, but also to promote differentiation events, in particular those leading to the generation of marginal zone B cells. 相似文献
90.
Steiner I 《Ceskoslovenská patologie》2005,41(1):7-11
The term acute aortic syndrome comprises in addition to classic dissection also two recently described entities--penetrating ulcer and intramural haematoma. Forty-two necropsy cases of acute aortic syndrome were encountered during the last six years--41 dissections and one penetrating ulcer; the intramural haematoma was not seen. According to the DeBakey classification, there were 26 dissections of type I, 8 of type II, 1 of type IIIA, and 4 of type IIIB; in 2 cases the dissection was confined to the abdominal aorta. The dissection had a chronic character in four cases. Aortic rupture was found in 24 cases (59%), most frequently (19x) into the pericardial cavity. The aortic dissection continued into aortic branches in 25 patients (61%), causing stenosis/obstruction of coronary arteries in 7, of branches of the arch in 20, of abdominal arteries in 12, and of renal arteries in 17 patients, respectively. Histologically, there were degenerative lesions of the Erdheim type in the media of 10 aortas (from 21 completely examined). As possible risk factors for aortic dissection there appeared hypertension in 32 patients, anuloaortic ectasia in 11, saccular aneurysm ot the abdominal aorta in 6, family history of dissection in 2, Marfan syndrome in 2, prolaps of the mitral valve in 2, and bicuspid aortic valve in 2 patients, respectively. The aortic dissection was iatrogenic in 7 patients, presenting as a complication of a cardiosurgical or invasive cardiological procedure. 相似文献