全文获取类型
收费全文 | 3931篇 |
免费 | 418篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 55篇 |
儿科学 | 279篇 |
妇产科学 | 90篇 |
基础医学 | 467篇 |
口腔科学 | 118篇 |
临床医学 | 461篇 |
内科学 | 713篇 |
皮肤病学 | 53篇 |
神经病学 | 289篇 |
特种医学 | 303篇 |
外科学 | 613篇 |
综合类 | 98篇 |
预防医学 | 308篇 |
眼科学 | 44篇 |
药学 | 219篇 |
中国医学 | 5篇 |
肿瘤学 | 246篇 |
出版年
2021年 | 44篇 |
2020年 | 33篇 |
2019年 | 53篇 |
2018年 | 80篇 |
2017年 | 81篇 |
2016年 | 77篇 |
2015年 | 67篇 |
2014年 | 91篇 |
2013年 | 146篇 |
2012年 | 174篇 |
2011年 | 151篇 |
2010年 | 135篇 |
2009年 | 139篇 |
2008年 | 159篇 |
2007年 | 130篇 |
2006年 | 142篇 |
2005年 | 131篇 |
2004年 | 136篇 |
2003年 | 107篇 |
2002年 | 136篇 |
2001年 | 109篇 |
2000年 | 116篇 |
1999年 | 94篇 |
1998年 | 96篇 |
1997年 | 88篇 |
1996年 | 99篇 |
1995年 | 79篇 |
1994年 | 61篇 |
1993年 | 69篇 |
1992年 | 96篇 |
1991年 | 102篇 |
1990年 | 77篇 |
1989年 | 60篇 |
1988年 | 87篇 |
1987年 | 85篇 |
1986年 | 87篇 |
1985年 | 67篇 |
1984年 | 45篇 |
1983年 | 45篇 |
1982年 | 36篇 |
1981年 | 40篇 |
1980年 | 32篇 |
1979年 | 38篇 |
1978年 | 23篇 |
1977年 | 31篇 |
1976年 | 37篇 |
1974年 | 30篇 |
1973年 | 26篇 |
1972年 | 28篇 |
1971年 | 27篇 |
排序方式: 共有4361条查询结果,搜索用时 15 毫秒
21.
The use of computer-based documentation tools confers many benefits to the delivery of evidence-based health care. We developed Clictate, a structured reporting environment that utilized standard WindowsTM-based data entry constructs and natural language generation. Clictate has been in use for over 3 years by pediatric providers in an ambulatory setting. More than 50% of our providers use Clictate during the patient encounter. This report describes our results to date, and suggests future opportunities for research and development in the area of computer-based documentation. 相似文献
22.
The synthesis of immunoglobulins by the uterine cervix was investigated in an endocervical organ-culture system. Using Ouchterlony immunodiffusion gels immunoglobulin G, immunoglobulin A and secretory piece were detected in washings of endocervical explants and in explant incubation medium. Synthesis of immunoglobulin in the organ-culture system was investigated by polyacrylamide-gel electrophoresis of radiolabelled polypeptides; 2 polypeptides co-migrated with the heavy and light chains of a reference polyclonal immunoglobulin G and were confirmed, by use of anti-human globulin and iodinated staphylococcal protein A, to be the heavy and light chains of immunoglobulin G. This experimental system will provide a useful model in future investigations of the efficacy of a local vaccine in human subjects. 相似文献
23.
We report an infant with multiple congenital anomalies, including craniosynostosis, tetralogy of Fallot variant, and limb anomalies associated with a maternal deletion of 15q15-22.1. Only two other patients have been reported with a similar deletion, but the deletion was paternal in both cases. We review our patient's findings and compare them to previously reported individuals with similar 15q abnormalities. Our patient allows an expansion of phenotype associated with mid-15q deletions to include severe craniosynostosis, congenital heart disease, and limb anomalies. This will assist in prenatal counseling and predicting postnatal outcome for other affected individuals. The specific breakpoints in our patient and the other patients with similar deletions may also assist in determining a critical region for suture formation. 相似文献
24.
25.
P J Lamey R E Leake S K Cowan D S Soutar I A McGregor F M McGregor 《Journal of clinical pathology》1987,40(5):532-534
Major salivary gland tumours were studied for the presence of hormone receptors for oestrogen and progesterone. Of the eight salivary gland tumours exhibiting varied histology, none showed high affinity receptors for oestrogen or progesterone. Salivary tissue from four patients with non-neoplastic salivary gland disease was also studied and found not to contain high affinity receptor sites. The absence of hormone receptors in these glands suggests that such tumours are not dependent on endocrine function. 相似文献
26.
Multiple mechanisms govern the dynamics of depression at neocortical synapses of young rats 总被引:2,自引:0,他引:2
Galit Fuhrmann Anna Cowan Idan Segev Misha Tsodyks Christian Stricker 《The Journal of physiology》2004,557(2):415-438
Synaptic transmission between pairs of excitatory neurones in layers V ( N = 38) or IV ( N = 6) of somatosensory cortex was examined in a parasagittal slice preparation obtained from young Wistar rats (14–18 days old). A combined experimental and theoretical approach reveals two characteristics of short-term synaptic depression. Firstly, as well as a release-dependent depression, there is a release-independent component that is evident in smaller postsynaptic responses even following failure to release transmitter. Secondly, recovery from depression is activity dependent and is faster at higher input frequencies. Frequency-dependent recovery is a Ca2+ -dependent process and does not reflect an underlying augmentation. Frequency-dependent recovery and release-independent depression are correlated, such that at those connections with a large amount of release-independent depression, recovery from depression is faster. In addition, both are more pronounced in experiments performed at physiological temperatures. Simulations demonstrate that these homeostatic properties allow the transfer of rate information at all frequencies, essentially linearizing synaptic responses at high input frequencies. 相似文献
27.
28.
Selective hyperthermia can be a feasible treatment modality for deep tissue abnormalities. It is accomplished by using a laser or ultrasound noninvasively to transfer energy to a desired target causing tissue damage. This process has two potential benefits to medical professionals: simplicity of procedure and safety to patient. However, optimizing these selective interactions is difficult due to the number of variables. We propose an optimization coefficient relating the dynamic and geometric parameters of selective hyperthermia, and proceed to measure it in an experimental setup consisting of a near-infrared laser and laser-absorbing dye. To simulate tissue, gelatin phantoms are created using a combination of water, intralipid, and gelatin. Our experiments use a 1.00-cm-diam spherical phantom that is homogeneously enhanced with an indocyanine green (ICG) solution and placed inside a nontarget phantom and irradiated by an 805-nm diode laser. Temperature measurements taken at different locations are analyzed so optimization coefficients can be calculated for different parameters. This optimization coefficient compares the difference in temperatures from inside and outside the target. Analysis of the values after thermal equilibrium provides information about the best parameter selection. Our findings indicate that the optimal ICG concentration and power combination for our tested parameters are 0.083% and 0.97 W, respectively. Based on our analysis, optimization can be obtained by using this coefficient to compare the selectivity of several parameter combinations. 相似文献
29.
Dal Zotto L; Quaderi NA; Elliott R; Lingerfelter PA; Carrel L; Valsecchi V; Montini E; Yen CH; Chapman V; Kalcheva I; Arrigo G; Zuffardi O; Thomas S; Willard HF; Ballabio A; Disteche CM; Rugarli EI 《Human molecular genetics》1998,7(3):489-499
We have recently reported isolation of the gene responsible for X- linked
Opitz G/BBB syndrome, a defect of midline development. MID1 is located on
the distal short arm of the human X chromosome (Xp22. 3) and encodes a
novel member of the B box family of zinc finger proteins. We have now
cloned the murine homolog of MID1 and performed preliminary expression
studies during development. Mid1 expression in undifferentiated cells in
the central nervous, gastrointestinal and urogenital systems suggests that
abnormal cell proliferation may underlie the defect in midline development
characteristic of Opitz syndrome. We have also found that Mid1 is located
within the mouse pseudoautosomal region (PAR) in Mus musculus , while it
seems to be X- specific in Mus spretus. Therefore, Mid1 is likely to be a
recent acquisition of the M. musculus PAR. Genetic and FISH analyses also
demonstrated a high frequency of unequal crossovers in the murine PAR,
creating spontaneous deletion/duplication events involving Mid1. These data
provide evidence for the first time that genetic instability of the PAR may
affect functionally important genes. In addition, we show that MID1 is the
first example of a gene subject to X-inactivation in man while escaping it
in mouse. These data contribute to a better understanding of the molecular
content and evolution of the rodent PAR.
相似文献
30.
Determination of the parent of origin in nine cases of prenatally detected chromosome aberrations found after intracytoplasmic sperm injection 总被引:1,自引:17,他引:1
Van Opstal D; Los FJ; Ramlakhan S; Van Hemel JO; Van Den Ouweland AM; Brandenburg H; Pieters MH; Verhoeff A; Vermeer MC; Dhont M; In't Veld PA 《Human reproduction (Oxford, England)》1997,12(4):682-686
Prenatal cytogenetic analysis of 71 fetuses conceived by intracytoplasmic
sperm injection (ICSI) resulted in the detection of nine (12.7%) chromosome
aberrations including two cases of 47,XXY, four cases involving a 45,X cell
line and three autosomal trisomies. Molecular analysis of the parental
origin of the deleted or supernumerary chromosome was performed by using
polymorphic microsatellite markers. Six cases involving a sex chromosome
abnormality were found to be of paternal origin while the two trisomic
cases that could be analysed were of maternal origin. Two cases involved
the same infertile couple who had two consecutive ICSI pregnancies
terminated because of a chromosome abnormality. The replaced embryos in
both cases originated from a single batch of ICSI fertilized oocytes of
which part was used to initiate the first pregnancy and part was
cryopreserved and used to initiate the second pregnancy.
相似文献