首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1313689篇
  免费   97022篇
  国内免费   2119篇
耳鼻咽喉   18606篇
儿科学   43506篇
妇产科学   38914篇
基础医学   192326篇
口腔科学   35841篇
临床医学   113909篇
内科学   258519篇
皮肤病学   27220篇
神经病学   103108篇
特种医学   50741篇
外国民族医学   367篇
外科学   200665篇
综合类   27237篇
现状与发展   1篇
一般理论   339篇
预防医学   97126篇
眼科学   29843篇
药学   100504篇
  1篇
中国医学   2565篇
肿瘤学   71492篇
  2018年   12681篇
  2016年   10801篇
  2015年   12520篇
  2014年   17181篇
  2013年   26183篇
  2012年   36271篇
  2011年   38800篇
  2010年   22677篇
  2009年   21455篇
  2008年   37582篇
  2007年   40746篇
  2006年   41375篇
  2005年   40608篇
  2004年   39167篇
  2003年   37994篇
  2002年   37335篇
  2001年   58440篇
  2000年   59839篇
  1999年   51023篇
  1998年   14680篇
  1997年   13204篇
  1996年   13414篇
  1995年   12678篇
  1994年   12007篇
  1993年   11132篇
  1992年   41166篇
  1991年   40538篇
  1990年   40045篇
  1989年   38869篇
  1988年   36281篇
  1987年   35477篇
  1986年   33842篇
  1985年   32269篇
  1984年   24091篇
  1983年   20992篇
  1982年   12596篇
  1981年   11089篇
  1979年   22737篇
  1978年   15978篇
  1977年   13834篇
  1976年   13048篇
  1975年   14259篇
  1974年   16756篇
  1973年   16126篇
  1972年   15364篇
  1971年   14251篇
  1970年   13242篇
  1969年   12760篇
  1968年   11995篇
  1967年   10488篇
排序方式: 共有10000条查询结果,搜索用时 781 毫秒
991.
992.
993.
994.
995.
996.
997.
The aim of the study was to explore the relationship between alexithymia and machiavellianism in a group of 201 university students. The subjects filled out the TAS-20 and the MACH-IV forms. The results showed firstly, a significant correlation between the two total scores (r = 0.35, P < 0.05), and secondly between the identification of feelings subscale of the TAS-20 and the opinions about human nature subscale of the Mach-IV (r = 0.44, P < 0.05). The results were discussed in light of the different factors (depression, dependency, psychoticism…) that could explain the relationship between the two concepts.  相似文献   
998.
OBJECTIVE: To introduce 1,1,1,2 tetrafluoroethane (TFE), as a new material for cryosurgery of gingival melanin pigmentation (GMP). STUDY DESIGN: Twenty-one patients with GMP were treated using a TFE-cooled cotton swab. Standard digital images of pigmented areas were measured preoperatively and postoperatively with image-analyzing software. The Mann-Whitney U test was used for statistical analysis. RESULTS: Keratinization was completed 3 to 4 weeks after application, without any trace of pigmentation. Statistical analysis revealed a significant difference between preoperative and postoperative measurements of pigmented areas (P < .05). During the follow-up period, no side effects were observed and improved esthetics were maintained up to month 30. CONCLUSIONS: The clinical outcomes of cryosurgery with TFE for treatment of GMP are very satisfactory. The use of TFE for cryosurgical treatment of GMP is practical and inexpensive. Moreover, unlike other cryosurgery methods no special equipment is required, and it is safe to store in the dental clinic.  相似文献   
999.
Background: Sudden, intraoperative cardiovascular deterioration as a result of pulmonary embolization of bone marrow fat is a potentially fatal complication during total hip and knee arthroplasty, intramedullary nailing, and spine surgery. Anesthetic management is challenging in the presence of increased right ventricular afterload due to pulmonary hypertension. Selective pulmonary vasodilation may be an appropriate prophylactic or therapeutic measure. The effect of sildenafil (phosphodiesterase inhibitor) on cardiovascular deterioration after bone marrow fat embolization was therefore investigated.

Methods: Bone cement (polymethylmethacrylate) was injected into three lumbar vertebrae in 12 sheep. Invasive blood pressures and heart rate were recorded continuously until 60 min after the last injection. Cardiac output and arterial and mixed venous blood gas variables were measured at selected time points. Before the first cement injection, 6 animals received a bolus injection (0.7 mg/kg) of sildenafil, with continuous infusion (0.2 mg [middle dot] kg-1 [middle dot] h-1) thereafter. Postmortem lung and kidney biopsies were taken for semiquantitative analysis of intravascular fat.

Results: Fat embolism was associated with a transient increase (21 +/- 7mmHg) in pulmonary arterial pressure. A transient decrease in arterial blood pressure and temporary increases in central venous pressure and dead space were also observed. No significant changes in any cardiovascular variable were observed after fat embolism in the sildenafil group. There was significantly (P < 0.05) less intravascular fat in the lungs of the sildenafil (median count of 5 emboli per microscopic view) compared with the control group (median count of 1).  相似文献   

1000.
BACKGROUND CONTEXT: Spinal manipulation (SM) is a form of manual therapy used clinically to treat patients with low back and neck pain. The most common form of this maneuver is characterized as a high-velocity (duration <150 ms), low-amplitude (segmental translation <2 mm, rotation <4 degrees , and applied force 220-889 N) impulse thrust (high-velocity, low-amplitude spinal manipulation [HVLA-SM]). Clinical skill in applying an HVLA-SM lies in the practitioner's ability to control the duration and magnitude of the load (ie, the rate of loading), the direction in which the load is applied, and the contact point at which the load is applied. Control over its mechanical delivery is presumably related to its clinical effects. Biomechanical changes evoked by an HVLA-SM are thought to have physiological consequences caused, at least in part, by changes in sensory signaling from paraspinal tissues. PURPOSE: If activation of afferent pathways does contribute to the effects of an HVLA-SM, it seems reasonable to anticipate that neural discharge might increase or decrease in a nonlinear fashion as the thrust duration approaches a threshold value. We hypothesized that the relationship between the duration of an impulsive thrust to a vertebra and paraspinal muscle spindle discharge would be nonlinear with an inflection near the duration of an HVLA-SM delivered clinically (<150 ms). In addition, we anticipated that muscle spindle discharge would be more sensitive to larger amplitude thrusts. STUDY DESIGN/SETTING: A neurophysiological study of spinal manipulation using the lumbar spine of a feline model. METHODS: Impulse thrusts (duration: 12.5, 25, 50, 100, 200, and 400 ms; amplitude 1 or 2 mm posterior to anterior) were applied to the spinous process of the L6 vertebra of deeply anesthetized cats while recording single unit activity from dorsal root filaments of muscle spindle afferents innervating the lumbar paraspinal muscles. A feedback motor was used in displacement control mode to deliver the impulse thrusts. The motor's drive arm was securely attached to the L6 spinous process via a forceps. RESULTS: As thrust duration became shorter, the discharge of the lumbar paraspinal muscle spindles increased in a curvilinear fashion. A concave-up inflection occurred near the 100-ms duration eliciting both a higher frequency discharge compared with the longer durations and a substantially faster rate of change as thrust duration was shortened. This pattern was evident in paraspinal afferents with receptive fields both close and far from the midline. Paradoxically, spindle afferents were almost twice as sensitive to the 1-mm compared with the 2-mm amplitude thrust (6.2 vs. 3.3 spikes/s/mm/s). This latter finding may be related to the small versus large signal range properties of muscle spindles. CONCLUSIONS: The results indicate that the duration and amplitude of a spinal manipulation elicit a pattern of discharge from paraspinal muscle spindles different from slower mechanical inputs. Clinically, these parameters may be important determinants of an HVLA-SM's therapeutic benefit.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号