全文获取类型
收费全文 | 383544篇 |
免费 | 14851篇 |
国内免费 | 522篇 |
专业分类
耳鼻咽喉 | 3669篇 |
儿科学 | 13759篇 |
妇产科学 | 7757篇 |
基础医学 | 45316篇 |
口腔科学 | 9905篇 |
临床医学 | 30552篇 |
内科学 | 76505篇 |
皮肤病学 | 5818篇 |
神经病学 | 34586篇 |
特种医学 | 14918篇 |
外国民族医学 | 26篇 |
外科学 | 52723篇 |
综合类 | 4067篇 |
现状与发展 | 1篇 |
一般理论 | 122篇 |
预防医学 | 40583篇 |
眼科学 | 6482篇 |
药学 | 21933篇 |
2篇 | |
中国医学 | 1358篇 |
肿瘤学 | 28835篇 |
出版年
2023年 | 1272篇 |
2022年 | 2477篇 |
2021年 | 4797篇 |
2020年 | 3305篇 |
2019年 | 4755篇 |
2018年 | 27340篇 |
2017年 | 21422篇 |
2016年 | 23414篇 |
2015年 | 6091篇 |
2014年 | 7813篇 |
2013年 | 9984篇 |
2012年 | 20765篇 |
2011年 | 35001篇 |
2010年 | 25812篇 |
2009年 | 17962篇 |
2008年 | 30330篇 |
2007年 | 33151篇 |
2006年 | 11959篇 |
2005年 | 13657篇 |
2004年 | 14266篇 |
2003年 | 14261篇 |
2002年 | 10269篇 |
2001年 | 5542篇 |
2000年 | 5581篇 |
1999年 | 4788篇 |
1998年 | 2240篇 |
1997年 | 1854篇 |
1996年 | 1687篇 |
1995年 | 1499篇 |
1994年 | 1417篇 |
1993年 | 1286篇 |
1992年 | 2862篇 |
1991年 | 2800篇 |
1990年 | 2593篇 |
1989年 | 2515篇 |
1988年 | 2272篇 |
1987年 | 2070篇 |
1986年 | 1939篇 |
1985年 | 1875篇 |
1984年 | 1371篇 |
1983年 | 1128篇 |
1982年 | 715篇 |
1981年 | 635篇 |
1980年 | 635篇 |
1979年 | 985篇 |
1978年 | 677篇 |
1977年 | 528篇 |
1975年 | 581篇 |
1974年 | 592篇 |
1973年 | 574篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
María de Gracia García-Martín María Violante de Paz Juan Antonio Galbis 《Macromolecular chemistry and physics.》1997,198(1):219-227
A chiral poly(3-substituted isobutyl D -aspartate) 12 was synthesized by polymerization of the chiral β-lactam 11 derived from D -glyceraldehyde. The new polyamide was characterized by elemental analyses, and infrared, 1H- and 13C nuclear magnetic resonance spectroscopies. The molecular weight was estimated as 543 000 and 230 000 on the basis of viscosimetric measurements and gel-permeation chromatography, respectively. Polyamide 12 is soluble in a variety of organic solvents including chloroform. 相似文献
992.
C. L. G. Ham J. M. L. Engels G. T. van de Wiel A. Machielsen 《Journal of magnetic resonance imaging : JMRI》1997,7(5):933-937
The application of high gradient amplitudes and switching rates for MRI and spectroscopy, resulting in short rise times for the gradient field and high changes of the magnetic flux density in the patient, is known to possibly evoke peripheral nerve stimulation (PNS) in patients. These effects have been studied on 20 volunteers under different experimental circumstances. The results of these measurements are partially in line with earlier findings reported in the literature. New information is found for the dependence of the PNS threshold level as a function of the rise time of the gradient waveform. The PNS threshold level, expressed in terms of dB/dt, is found to be proportional with t?05, where t is the switch time for the gradients. Indications are found that |B|, the modulus of the gradient vector field, is more closely related to the PNS threshold level than Bz, the imaging component of the gradient field. From the experiments, it is furthermore concluded that only for the imaging protocols characterized by the application of long bipolar repetitive gradient pulse trains, such as echo-planar imaging, PNS is expected at the reported threshold levels. For the protocols based on spin echo, turbo spin echo, inversion recovery, fast field echo, etc., characterized by shorter gradient pulse trains, the threshold levels are expected to be much higher. 相似文献
993.
Cynthia S. Pomerleau Anne W. Garcia Ovide F. Pomerleau Oliver G. Cameron 《Psychoneuroendocrinology》1992,17(6):627-638
Nicotine intake, menstrual and smoking withdrawal symptomatology, and baseline cortisol and MHPG were assessed in nine women smokers under conditions of ad lib smoking and overnight abstinence in three menstrual phases (early follicular, mid-to-late follicular, and late luteal). A trend towards higher nicotine intake p <0.100 was observed in the mid-to-late follicular phase. Although me menstrual symptomatology was not significantly elevated during the smoking abstinence condition overall, abstinence appeared to prevent the normal reduction in symptomatology during the mid-to-late follicular phase that occurred under conditions of ad lib smoking. Menstrual and withdrawal symptoms were highly correlated, and both were most pronounced during the late luteal/abstinence condition. The smoking-specific item “craving” reflected this pattern, though in attenuated form, suggesting that the observed exacerbation of withdrawal symptomatology was not simply due to generalized dysphoria, as queried in both instruments. MHPG was significantly elevated in the late luteal phase, whereas cortisol was significantly higher during ad lib smoking than during abstinence and tended to be highest in the mid-to-late follicular phase. Further investigation will be needed to determine the functional significance of these findings for understanding and treating smoking in women. 相似文献
994.
995.
996.
J B van de Biezenbos J G Nijhuis H G Brunner 《Nederlands tijdschrift voor geneeskunde》1992,136(50):2480-2482
We describe the maternal and neonatal complications of pregnancy in two patients with myotonic dystrophy. The disease leads to an increased spontaneous abortion rate, hydramnios, prolonged first and second stages of labour, retained placenta, postpartum haemorrhages and anaesthetic sensitivity in the mother. The neonatal problems are caused by the congenital form of the disease. The major clinical features of congenital myotonic dystrophy are bilateral facial weakness, hypotonia, neonatal distress, feeding difficulties, talipes, tent-shaped mouth, mental retardation and delayed motor development. Relatives of a known myotonic dystrophy patient should be advised to let themselves be examined for this disease. If the disease is diagnosed, information should be given regarding possibilities for prenatal diagnosis. Pregnancy in myotonic dystrophy patients should be monitored by a gynaecologist. Labour has to take place in a hospital with intensive care facilities for mother and child. 相似文献
997.
Frédéric Bruckert Eric de Kerviler Anne-Marie Zagdanski Jean-Michel Molina Isabelle Casin A. Guermazi Janine Bédrossian Jacques Frija 《Skeletal radiology》1997,26(7):431-433
Bartonella henselae, previously called Rochalimaea henselae, is the causative agent of cat scratch disease (CSD) in immunocompetent subjects and bacillary angiomatosis in immunocompromised
ones. Bone lesions are common in bacillary angiomatosis, but not in CSD. We present the case of a patient with a renal transplant
treated by immunosuppressive therapy who developed a sternal abscess with a histological pattern of CSD. The CT pattern was
that of a lytic bone lesion with adjacent fluid collection. The diagnosis was made on the basis of a polymerase chain reaction
amplification performed on bone material. Bartonella henselae is a newly described bacteria that causes CSD in a normal host and bacillary angiomatosis in immunocompromised patients. We
report a case of an osteolytic lesion of the sternum with adjacent fluid collection related to CSD, which occurred in a patient
with a renal transplant. 相似文献
998.
999.
P. Lips MD C. Cooper D. Agnusdei F. Caulin P. Egger O. Johnell J. A. Kanis U. Liberman H. Minne J. Reeve J. Y. Reginster M. C. de Vernejoul I. Wiklund 《Osteoporosis international》1997,7(1):36-38
The morbidity of osteoporosis is caused by fractures. Vertebral fractures lead to pain and disability and a decrease in quality of life. A Working Party of the European Foundation for Osteoporosis has developed a specific questionnaire for patients with established vertebral osteoporosis. This questionnaire is intended for use in clinical trials. The questionnaire consists of questions and visual analogue scales in the following domains: pain, activities of daily living, jobs around the house, mobility, leisure and social activities, general health perception and mood. The questionnaire has been translated from English into French, German, Italian, Hebrew, Swedish and Dutch. The questionnaire is currently being validated in a multicentre study involving patients with stable osteoporosis and control subjects. Preliminary results indicate that the reproducibility is sufficient and that the questionnaire is able to discriminate between patients with vertebral osteoporosis and control subjects. 相似文献
1000.
To obviate the need for general anesthesia or dissection of the rectus sheath, we have transferred laparoscopic herniorrhaphy back to the groin by first dissecting the suprainguinal parietoperitoneal space of Bogros via the femoral canal. Cadaver dissections demonstrated that the preperitoneal plane could be routinely fingered and distended with a digitally placed balloon introduced through a 1-cm incision immediately below the inguinal ligament. A 10-mm femoral laparoscopic port was then inserted and pressurized, allowing two standard 5-mm ports to be introduced from above, through the lower quadrant, under vision. The procedure was then carried out in the usual way, the mesh being inserted from below. Ten patients (two women), 23–73 years old, selected because general anesthesia was inadvisable, underwent uncomplicated prosthetic repair of unilateral (eight) or bilateral (two) inguinal defects. Half of the peritoneal sacs were pushed up and out of the inguinal canal; 18 months later there were no recurrences (inguinal or femoral). Preliminary experience with this new technique is promising. It may prove applicable to retroperitoneal exposure of the distal aorta and iliac vessels, allowing laparoscopic bypass for Leriche syndrome. 相似文献