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151.
The characteristics of deformation failure and stress brittle drop of granite under loading and unloading conditions are studied respectively based on two unloading stress path cases and conventional triaxial compression experiments. The experiments show that the primary deformation of rock is rebound or tension in the (main) unloading direction, but plastic deformation in the non or sub unloading direction is not significant. And the curves of stress strain after peak strength present obvious brittle. Whilst the primary deformation of rock under loading is axial pressure deformation, and plastic deformation increases with the raise of confining pressure. The fracture is characterized by strong tensile, and all tensile cracks are fully developed. Furthermore, when the rock samples are unloaded in two directions, and even normal to unloading direction, sub unloading annular tensile cracks are produced. The shear fractures is obvious comparatively when confining pressure becomes higher, and it develops following tensile cracks with more micro tension cracks formed in two sides along shear plane. But the fracture is characterized by shear under conventional triaxial compression with little tensile cracks; the coefficients of brittles stress drop of granite is increased with the growth of confining pressure under conventional triaxial compression and reduced under unloading. When the initial confining pressure is the same, the coefficients of brittles stress drop under unloading is less than that under loading. In SchemeⅡ, the coefficients of brittles stress drop reaches negative when initial confining pressure is up to 30 MPa, and the one (R)is RⅢ>RⅠ>RⅡ in three test cases. 相似文献
152.
In the analysis of rock burst criterion prediction at home and abroad, the prediction standards of rock burst are selected including the conditions of mechanics、integrity、energy and brittle. The concept of relative membership degree on the rock burst prediction was introduced. The weight of standards and fuzzy matrix of relative membership degree are calculated. Uncertainty in rock burst prediction is described and compared according to the information entropy. Generalized weighted distance is also defined to characterize the differences in rock burst based on the maximum entropy principle, the establishment of a rock burst prediction fuzzy optimization model. The results from the application to practical example and comparisons with other methods are fairly good. Finally, the prediction model is applied in Putaoshan tunnel and the predictions are consistent with the actual rock burst. 相似文献
153.
GUO Chao ZHANG Yong-xing LUO Jun-cai ZHOU Zhi-ming ZHANG bo-hu LI Jin-long XIE Wen-ting WU De-jun 《保鲜与加工》2011,(4):106-112
By using near crack line analysis method and Mohr-Coulomb strength criterion,the elastic-plastic solution for near crack line of an eccentric cracks loaded by the pore water pressure under large scale yielding condition is analyzed.The elastic stress fields,the plastic stress field,the unit normal vector of the elastic-plastic boundary near the crack line,the elastic-plastic stress fields near crack line are identified.The change pattern of the length of the plastic zone and the pore water pressure is presented.Besides,the elastic-plastic analytical solution for an eccentric cracks loaded by the pore water pressure is obtained. 相似文献
154.
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156.
体外成熟培养和牛老化卵受精后发育到囊胚到期速度减慢。囊胚期的发育率分别为22h培养组的35.3%,34h组23.6%,46h组15.4%,胚胎的发育速度随培养时间的延长而明显减慢(P<0.05)。46h组的囊胚期胚胎的平均卵裂球数明显少于22h组(P<0.05),老化组的染色体平均分裂像,分裂指数均明显低于对照组(P<0.05)。染色体异常发生率46h组高于22h组。 相似文献
157.
158.
顺式氯氰菊酯微乳液的微观结构 总被引:2,自引:0,他引:2
利用粘度法和电导法研究了顺式氯氰菊酯微乳液微观结构的变化,对其形成机理进行了探讨,并用偏光显微镜和透射电镜等手段进行了表征。研究发现顺式氯氰菊酯微乳液体系随水相含量的增加分别形成了W/O型微乳液、层状液晶、双连续结构和O/W型微乳液;表面活性剂和醇分子之间依靠氢键和范德华力形成各向异性的类线形大分子,被破坏和重排是层状液晶结构区显示出异常流变特性和不规则电导率变化的主要原因。 相似文献
159.
“施丰乐”是根据植物生长发育特性,采用无机营养元素和有机营养物质为原料,经特殊工艺制得的集营养与调节于一体的新型高效强力肥。为探索其在开阳县气候、土壤等条件下对小麦生长及产量的效果,为生产上能否扩大推广使用提供依据,我们进行了本试验。 1 材料与方法 1.1 试验地概况 试验于1999年10月25日至2000年5月30日在开阳县冯三镇坪上村进行。海拔1050m,年均温15.5℃,年均日照时数1325.6h,年降雨量1100mm,无霜期288d。旱地、黄泥土,肥力中等,土壤pH值为5.4。前作玉米,小麦品种为“兴麦17号”。 试验按设计要求实行1.67m开厢,分带种植,每小区种4厢,每厢播面0.5m,种4行,实行小窝疏株密植,并按厢定量匀施底肥。 每小区底肥种类与用量是:火土灰30kg,厩肥120kg,N∶P∶K(8∶8∶9)复混肥2.5kg,折合667m2用量:火土灰600kg,厩肥2400kg,8∶8∶9复混肥50kg。土肥拌匀后,按小区定量播种,播种量为300g/小区,折合667m2播种量为6kg。播前先晒种半天,然后按设计预先浸种后播种。在生长过程中于分蘖初期用尿素追肥1次,用量为0.75kg/小区,折合667m2用量为15kg。 1.2 试验设计 从小麦分蘖初期开始,用四川省施丰乐科技产业有限公司独家生产的“施丰乐”高效强力肥进行小区喷施比较试验。设3个处理,采取随机区组排列,3次重复,共9个小区,小区面积33.35 m2(0.05亩)。3个处理分别为:a.对照处理:不用“施丰乐”;b.按667m2用“施丰乐”1 g对水30 kg进行喷施;c.按667m2用“施丰乐”2g对水30kg进行喷施。 相似文献
160.